Remove dependency on libevent (#41486)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/41486

Now that React-Hermes does not depends on folly::Futures anymore, we can safely delete the `libevent` dependency.
This will speedup the pod install step and potentially also the bundle size (to be tested)

## Changelog
[iOS][Removed] - Remove libevent dependency

Reviewed By: javache

Differential Revision: D51307333

fbshipit-source-id: 029c1d6aaad46fc261502241f7df28b4d5f59eb9

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

@@ -35,7 +35,7 @@ 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" => "\"${PODS_ROOT}/hermes-engine/destroot/include\" \"$(PODS_TARGET_SRCROOT)/..\" \"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/RCT-Folly\" \"$(PODS_ROOT)/DoubleConversion\" \"$(PODS_ROOT)/fmt/include\" \"$(PODS_ROOT)/libevent/include\"",
+                               "HEADER_SEARCH_PATHS" => "\"${PODS_ROOT}/hermes-engine/destroot/include\" \"$(PODS_TARGET_SRCROOT)/..\" \"$(PODS_ROOT)/boost\" \"$(PODS_ROOT)/RCT-Folly\" \"$(PODS_ROOT)/DoubleConversion\" \"$(PODS_ROOT)/fmt/include\"",
                                "CLANG_CXX_LANGUAGE_STANDARD" => "c++20"
                              }
   s.header_dir             = "reacthermes"

packages/react-native/scripts/cocoapods/__tests__/jsengine-test.rb

@@ -67,13 +67,12 @@ class JSEngineTests < Test::Unit::TestCase
         setup_hermes!(:react_native_path => @react_native_path)
 
         # Assert
-        assert_equal($podInvocationCount, 4)
+        assert_equal($podInvocationCount, 3)
         assert_equal($podInvocation["React-jsi"][:path], "../../ReactCommon/jsi")
         hermes_engine_pod_invocation = $podInvocation["hermes-engine"]
         assert_equal(hermes_engine_pod_invocation[:podspec], "../../sdks/hermes-engine/hermes-engine.podspec")
         assert_equal(hermes_engine_pod_invocation[:tag], "")
         assert_equal($podInvocation["React-hermes"][:path], "../../ReactCommon/hermes")
-        assert_equal($podInvocation["libevent"][:version], "~> 2.1.12")
     end
 
 end

packages/react-native/scripts/cocoapods/jsengine.rb

@@ -30,5 +30,4 @@ def setup_hermes!(react_native_path: "../node_modules/react-native")
     hermestag = File.exist?(hermestag_file) ? File.read(hermestag_file).strip : ''
     pod 'hermes-engine', :podspec => "#{react_native_path}/sdks/hermes-engine/hermes-engine.podspec", :tag => hermestag
     pod 'React-hermes', :path => "#{react_native_path}/ReactCommon/hermes"
-    pod 'libevent', '~> 2.1.12'
 end

packages/react-native/scripts/cocoapods/utils.rb

@@ -592,7 +592,6 @@ class ReactNativePodsUtils
             "fmt",
             "glog",
             "hermes-engine",
-            "libevent",
             "React-hermes",
         ]
     end