Add automatic signature generation for embind symbols (#19242)

I had to jump through a few hoops here to get the C++ files to be
include-able in the sig-generating program, but I think it worth it.

src/embind/embind.js

@@ -399,7 +399,6 @@ var LibraryEmbind = {
     return impl;
   },
 
-  _embind_register_void__sig: 'vpp',
   _embind_register_void__deps: ['$readLatin1String', '$registerType'],
   _embind_register_void: function(rawType, name) {
     name = readLatin1String(name);
@@ -417,7 +416,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_bool__sig: 'vpppii',
   _embind_register_bool__deps: [
     '$getShiftFromSize', '$readLatin1String', '$registerType'],
   _embind_register_bool: function(rawType, name, size, trueValue, falseValue) {
@@ -524,7 +522,6 @@ var LibraryEmbind = {
 
   // When converting a number from JS to C++ side, the valid range of the number is
   // [minRange, maxRange], inclusive.
-  _embind_register_integer__sig: 'vpppii',
   _embind_register_integer__deps: [
     '$embindRepr', '$getShiftFromSize', '$integerReadValueFromPointer',
     '$readLatin1String', '$registerType'],
@@ -581,7 +578,6 @@ var LibraryEmbind = {
   },
 
 #if WASM_BIGINT
-  _embind_register_bigint__sig: 'vpppjj',
   _embind_register_bigint__deps: [
     '$embindRepr', '$readLatin1String', '$registerType', '$integerReadValueFromPointer'],
   _embind_register_bigint: function(primitiveType, name, size, minRange, maxRange) {
@@ -620,7 +616,6 @@ var LibraryEmbind = {
   _embind_register_bigint: function(primitiveType, name, size, minRange, maxRange) {},
 #endif
 
-  _embind_register_float__sig: 'vppp',
   _embind_register_float__deps: [
     '$embindRepr', '$floatReadValueFromPointer', '$getShiftFromSize',
     '$readLatin1String', '$registerType'],
@@ -653,7 +648,6 @@ var LibraryEmbind = {
     return this['fromWireType']({{{ makeGetValue('pointer', '0', 'i32') }}});
   },
 
-  _embind_register_std_string__sig: 'vpp',
   _embind_register_std_string__deps: [
     '$readLatin1String', '$registerType',
     '$simpleReadValueFromPointer', '$throwBindingError',
@@ -758,7 +752,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_std_wstring__sig: 'vppp',
   _embind_register_std_wstring__deps: [
     '$readLatin1String', '$registerType', '$simpleReadValueFromPointer',
     '$UTF16ToString', '$stringToUTF16', '$lengthBytesUTF16',
@@ -835,7 +828,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_emval__sig: 'vpp',
   _embind_register_emval__deps: [
     '_emval_decref', '$Emval',
     '$readLatin1String', '$registerType', '$simpleReadValueFromPointer'],
@@ -860,7 +852,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_memory_view__sig: 'vpip',
   _embind_register_memory_view__deps: ['$readLatin1String', '$registerType'],
   _embind_register_memory_view: function(rawType, dataTypeIndex, name) {
     var typeMapping = [
@@ -1183,7 +1174,6 @@ var LibraryEmbind = {
     return fp;
   },
 
-  _embind_register_function__sig: 'vpippppi',
   _embind_register_function__deps: [
     '$craftInvokerFunction', '$exposePublicSymbol', '$heap32VectorToArray',
     '$readLatin1String', '$replacePublicSymbol', '$embind__requireFunction',
@@ -1207,7 +1197,6 @@ var LibraryEmbind = {
 
   $tupleRegistrations: {},
 
-  _embind_register_value_array__sig: 'vpppppp',
   _embind_register_value_array__deps: [
     '$tupleRegistrations', '$readLatin1String', '$embind__requireFunction'],
   _embind_register_value_array: function(
@@ -1226,7 +1215,6 @@ var LibraryEmbind = {
     };
   },
 
-  _embind_register_value_array_element__sig: 'vppppppppp',
   _embind_register_value_array_element__deps: [
     '$tupleRegistrations', '$embind__requireFunction'],
   _embind_register_value_array_element: function(
@@ -1250,7 +1238,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_finalize_value_array__sig: 'vp',
   _embind_finalize_value_array__deps: [
     '$tupleRegistrations', '$runDestructors',
     '$simpleReadValueFromPointer', '$whenDependentTypesAreResolved'],
@@ -1315,7 +1302,6 @@ var LibraryEmbind = {
 
   $structRegistrations: {},
 
-  _embind_register_value_object__sig: 'vpppppp',
   _embind_register_value_object__deps: [
     '$structRegistrations', '$readLatin1String', '$embind__requireFunction'],
   _embind_register_value_object: function(
@@ -1334,7 +1320,6 @@ var LibraryEmbind = {
     };
   },
 
-  _embind_register_value_object_field__sig: 'vpppppppppp',
   _embind_register_value_object_field__deps: [
     '$structRegistrations', '$readLatin1String', '$embind__requireFunction'],
   _embind_register_value_object_field: function(
@@ -1360,7 +1345,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_finalize_value_object__sig: 'vp',
   _embind_finalize_value_object__deps: [
     '$structRegistrations', '$runDestructors',
     '$simpleReadValueFromPointer', '$whenDependentTypesAreResolved'],
@@ -1985,7 +1969,6 @@ var LibraryEmbind = {
     };
   },
 
-  _embind_register_class__sig: 'vppppppppppppp',
   _embind_register_class__deps: [
     '$BindingError', '$ClassHandle', '$createNamedFunction',
     '$registeredPointers', '$exposePublicSymbol',
@@ -2096,7 +2079,6 @@ var LibraryEmbind = {
     );
   },
 
-  _embind_register_class_constructor__sig: 'vpipppp',
   _embind_register_class_constructor__deps: [
     '$heap32VectorToArray', '$embind__requireFunction', '$runDestructors',
     '$throwBindingError', '$whenDependentTypesAreResolved', '$registeredTypes',
@@ -2184,7 +2166,6 @@ var LibraryEmbind = {
                          classType.registeredClass);
   },
 
-  _embind_register_class_function__sig: 'vppippppii',
   _embind_register_class_function__deps: [
     '$craftInvokerFunction', '$heap32VectorToArray', '$readLatin1String',
     '$embind__requireFunction', '$throwUnboundTypeError',
@@ -2252,7 +2233,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_class_property__sig: 'vpppppppppp',
   _embind_register_class_property__deps: [
     '$readLatin1String', '$embind__requireFunction', '$runDestructors',
     '$throwBindingError', '$throwUnboundTypeError',
@@ -2324,7 +2304,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_class_class_function__sig: 'vppippppi',
   _embind_register_class_class_function__deps: [
     '$craftInvokerFunction', '$ensureOverloadTable', '$heap32VectorToArray',
     '$readLatin1String', '$embind__requireFunction', '$throwUnboundTypeError',
@@ -2382,7 +2361,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_class_class_property__sig: 'vpppppppp',
   _embind_register_class_class_property__deps: [
     '$readLatin1String', '$embind__requireFunction', '$runDestructors',
     '$throwBindingError', '$throwUnboundTypeError',
@@ -2446,7 +2424,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_create_inheriting_constructor__sig: 'pppp',
   _embind_create_inheriting_constructor__deps: [
     '$createNamedFunction', '$Emval',
     '$PureVirtualError', '$readLatin1String',
@@ -2530,7 +2507,6 @@ var LibraryEmbind = {
     return name;
   },
 
-  _embind_register_smart_ptr__sig: 'vpppipppppppp',
   _embind_register_smart_ptr__deps: ['$RegisteredPointer', '$embind__requireFunction', '$whenDependentTypesAreResolved'],
   _embind_register_smart_ptr: function(rawType,
                                        rawPointeeType,
@@ -2569,7 +2545,6 @@ var LibraryEmbind = {
     });
   },
 
-  _embind_register_enum__sig: 'vpppi',
   _embind_register_enum__deps: ['$exposePublicSymbol', '$getShiftFromSize', '$enumReadValueFromPointer',
     '$readLatin1String', '$registerType'],
   _embind_register_enum: function(rawType, name, size, isSigned) {
@@ -2595,7 +2570,6 @@ var LibraryEmbind = {
     exposePublicSymbol(name, ctor);
   },
 
-  _embind_register_enum_value__sig: 'vppp',
   _embind_register_enum_value__deps: ['$createNamedFunction', '$readLatin1String', '$requireRegisteredType'],
   _embind_register_enum_value: function(rawEnumType, name, enumValue) {
     var enumType = requireRegisteredType(rawEnumType, 'enum');
@@ -2611,7 +2585,6 @@ var LibraryEmbind = {
     Enum[name] = Value;
   },
 
-  _embind_register_constant__sig: 'vppd',
   _embind_register_constant__deps: ['$readLatin1String', '$whenDependentTypesAreResolved'],
   _embind_register_constant: function(name, type, value) {
     name = readLatin1String(name);