add x86_64 arm64-v8a support. Fixes #2814 (#18754)

Summary:
add arm64 support, related issue : facebook/react-native#2814.
If we are okay with binary aar android-jsc, then the pr can be directly merged. Otherwise merge facebookarchive/android-jsc#30 first and do a new release.

RNTester all variant works. You can also test the apk from here: https://github.com/gengjiawen/react-native/releases/tag/v0.56beta.

facebookarchive/android-jsc#30.

 [ANDROID] [ENHANCEMENT] [ABI] - add x86_64 arm64-v8a support.

Differential Revision: D9491481

Pulled By: hramos

fbshipit-source-id: d6ec6992768eb0c0866a0317273e09fae5b8935e

android/app/build.gradle

@@ -76,7 +76,7 @@ apply from: "../../../react.gradle"
  * Upload all the APKs to the Play Store and people will download
  * the correct one based on the CPU architecture of their device.
  */
-def enableSeparateBuildPerCPUArchitecture = false
+def enableSeparateBuildPerCPUArchitecture = true
 
 /**
  * Run Proguard to shrink the Java bytecode in release builds.
@@ -93,9 +93,6 @@ android {
         targetSdkVersion 27
         versionCode 1
         versionName "1.0"
-        ndk {
-            abiFilters "armeabi-v7a", "x86"
-        }
     }
     signingConfigs {
         release {
@@ -110,7 +107,7 @@ android {
             enable enableSeparateBuildPerCPUArchitecture
             universalApk false
             reset()
-            include "armeabi-v7a", "x86"
+            include "armeabi-v7a", "x86", "x86_64", "arm64-v8a"
         }
     }
     buildTypes {
@@ -123,20 +120,6 @@ android {
             signingConfig signingConfigs.release
         }
     }
-
-    // applicationVariants are e.g. debug, release
-    applicationVariants.all { variant ->
-        variant.outputs.each { output ->
-            // For each separate APK per architecture, set a unique version code as described here:
-            // http://tools.android.com/tech-docs/new-build-system/user-guide/apk-splits
-            def versionCodes = ["armeabi-v7a":1, "x86":2]
-            def abi = output.getFilter(OutputFile.ABI)
-            if (abi != null) {  // null for the universal-debug, universal-release variants
-                output.versionCodeOverride =
-                        versionCodes.get(abi) * 1048576 + defaultConfig.versionCode
-            }
-        }
-    }
 }
 
 dependencies {