Exclude Hermes debugger in release builds

Summary:
Fixes Xcode release builds when Hermes is enabled.

The Hermes debugger is loaded by the Hermes executor only if HERMES_ENABLE_DEBUGGER is defined. The hermes-engine Pod would set `HERMES_ENABLE_DEBUGGER=0` in release builds, but of course this would satisfy the HERMES_ENABLE_DEBUGGER ifdef check, leading to build time issues due to missing `hermes::debugger` symbols.

Now, both the `hermes-engine` and `React-hermes` pods only set `HERMES_ENABLE_DEBUGGER=1` in debug builds. No gcc preprocessor definition is added by these pods in release builds.

Changelog:
[iOS] [Changed] - Do not load Hermes inspector in release builds

Reviewed By: cipolleschi

Differential Revision: D40077503

fbshipit-source-id: dd9ce148e8521fc4e43e47e90f29ba8f7c9b7e4a

ReactCommon/hermes/React-hermes.podspec

@@ -5,6 +5,10 @@
 
 require "json"
 
+# Whether Hermes is built for Release or Debug is determined by the PRODUCTION envvar.
+build_type = ENV['PRODUCTION'] == "1" ? :release : :debug
+
+# package.json
 package = JSON.parse(File.read(File.join(__dir__, "..", "..", "package.json")))
 version = package['version']
 
@@ -25,7 +29,7 @@ Pod::Spec.new do |s|
   s.version                = version
   s.summary                = "-"  # TODO
   s.homepage               = "https://reactnative.dev/"
-  s.license                = package["license"]
+  s.license                = package['license']
   s.author                 = "Facebook, Inc. and its affiliates"
   s.platforms              = { :osx => "10.14", :ios => "12.4" }
   s.source                 = source
@@ -36,9 +40,8 @@ Pod::Spec.new do |s|
   s.public_header_files    = "executor/HermesExecutorFactory.h"
   s.compiler_flags         = folly_compiler_flags + ' ' + boost_compiler_flags
   s.pod_target_xcconfig    = {
-                               "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/..\" \"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/RCT-Folly\" \"$(PODS_ROOT)/DoubleConversion\" \"$(PODS_ROOT)/libevent/include\"",
-                               "GCC_PREPROCESSOR_DEFINITIONS" => "HERMES_ENABLE_DEBUGGER=1",
-                             }
+                               "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/..\" \"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/RCT-Folly\" \"$(PODS_ROOT)/DoubleConversion\" \"$(PODS_ROOT)/libevent/include\""
+                             }.merge!(build_type == :debug ? { "GCC_PREPROCESSOR_DEFINITIONS" => "HERMES_ENABLE_DEBUGGER=1" } : {})
   s.header_dir             = "reacthermes"
   s.dependency "React-cxxreact", version
   s.dependency "React-jsi", version

sdks/hermes-engine/hermes-engine.podspec

@@ -11,8 +11,7 @@ react_native_path = File.join(__dir__, "..", "..")
 build_type = ENV['PRODUCTION'] == "1" ? :release : :debug
 
 # package.json
-package_file = File.join(react_native_path, "package.json")
-package = JSON.parse(File.read(package_file))
+package = JSON.parse(File.read(File.join(react_native_path, "package.json")))
 version = package['version']
 
 # sdks/.hermesversion
@@ -59,11 +58,10 @@ Pod::Spec.new do |spec|
   spec.ios.vendored_frameworks = "destroot/Library/Frameworks/universal/hermes.xcframework"
   spec.osx.vendored_frameworks = "destroot/Library/Frameworks/macosx/hermes.framework"
 
-  spec.xcconfig            = {
-    "CLANG_CXX_LANGUAGE_STANDARD" => "c++17",
-    "CLANG_CXX_LIBRARY" => "compiler-default",
-    "GCC_PREPROCESSOR_DEFINITIONS" => "HERMES_ENABLE_DEBUGGER=#{build_type == :debug ? "1" : "0"}"
-  }
+  spec.xcconfig = {
+                    "CLANG_CXX_LANGUAGE_STANDARD" => "c++17",
+                    "CLANG_CXX_LIBRARY" => "compiler-default"
+                  }.merge!(build_type == :debug ? { "GCC_PREPROCESSOR_DEFINITIONS" => "HERMES_ENABLE_DEBUGGER=1" } : {})
 
   if source[:git] then
     ENV['REACT_NATIVE_PATH'] = react_native_path