Do not include two copies of JSI when using hermes-engine (#41499)

Summary:

After #38922 we consume JSI from `ReactCommon/jsi`, and ignore JSI that is distributed with `hermes-engine`.

This diff removes `include/jsi` from `source_files` of `hermes-engine` so we don't get two sets of JSI headers - one from `ReactCommon`, and the other one from `hermes-engine`.

This diff also fixes accidental breakage of ODR violation, which was first fixed here #35038
We will no longer compile JSI into `react-native` when linking against `hermes-engine`, which already has JSI in it.

Changelog: [iOS][Fixed] - Exclude JSI headers when using hermes-engine prebuilt.

Differential Revision: D51347562

packages/react-native/ReactCommon/jsi/React-jsi.podspec

@@ -46,9 +46,14 @@ Pod::Spec.new do |s|
   s.dependency "glog"
 
   s.source_files  = "**/*.{cpp,h}"
-  s.exclude_files = [
-                      "jsi/jsilib-posix.cpp",
-                      "jsi/jsilib-windows.cpp",
-                      "**/test/*"
-                    ]
+  exclude_files = [
+                    "jsi/jsilib-posix.cpp",
+                    "jsi/jsilib-windows.cpp",
+                    "**/test/*"
+                  ]
+  if js_engine == :hermes
+    # JSI is a part of hermes-engine. Including them also in react-native will violate the One Definition Rulle.
+    exclude_files += [ "jsi/jsi.cpp" ]
+  end
+  s.exclude_files = exclude_files
 end

packages/react-native/sdks/hermes-engine/hermes-engine.podspec

@@ -41,7 +41,7 @@ Pod::Spec.new do |spec|
 
     spec.subspec 'Pre-built' do |ss|
       ss.preserve_paths = ["destroot/bin/*"].concat(["**/*.{h,c,cpp}"])
-      ss.source_files = "destroot/include/**/*.h"
+      ss.source_files = "destroot/include/hermes/**/*.h"
       ss.header_mappings_dir = "destroot/include"
       ss.ios.vendored_frameworks = "destroot/Library/Frameworks/universal/hermes.xcframework"
       ss.osx.vendored_frameworks = "destroot/Library/Frameworks/macosx/hermes.framework"