Frequent macro redefinition warnings when compiling on NetBSD 7

[srorso]

softfloat_stdTypes #defines a macro for int32_t. So does the NetBSD version of stdint.h, which is included first. The second definition of the macro does not affect correct code generation. I suspect the #define in softfloat_stdTypes.h is an artifact of a prior mechanism for indicating to compilation units that the integer types had been defined. Issue discovered during investigation of Hercules issue #244.