Remove unused files and code for old JSC and gcc build (#23014)

Summary:
----------

1. Unused prebuilt old JSC for 64bits.
2. Folly patch for gcc build.
Pull Request resolved: https://github.com/facebook/react-native/pull/23014

Differential Revision: D13690139

Pulled By: cpojer

fbshipit-source-id: 64555f5b9a5fbd4156e42eeff13da721846c2521

ReactAndroid/build.gradle

@@ -85,17 +85,6 @@ task prepareFolly(dependsOn: dependenciesPath ? [] : [downloadFolly], type: Copy
     include "folly-${FOLLY_VERSION}/folly/**/*", 'Android.mk'
     eachFile { fname -> fname.path = (fname.path - "folly-${FOLLY_VERSION}/") }
     includeEmptyDirs = false
-
-    // Patch for folly build break on gcc 4.9 and could be removed after build by clang
-    filesMatching('**/container/detail/F14Policy.h') {
-        filter(ReplaceTokens, tokens: [
-                'ObjectHolder(Args&&... args) : value_{std::forward<Args>(args)...} {}': 'ObjectHolder(Args&&... args) : value_({std::forward<Args>(args)...}) {}',
-                'ObjectHolder(Args&&... args) : T{std::forward<Args>(args)...} {}'     : 'ObjectHolder(Args&&... args) : T({std::forward<Args>(args)...}) {}',
-        ],
-                beginToken: '',
-                endToken: '')
-    }
-
     into "$thirdPartyNdkDir/folly"
 }