dynamically load JavaScriptCore with RTLD_LOCAL option

Reviewed By: tadeuzagallo

Differential Revision: D3703415

fbshipit-source-id: c67865b7fe75c21a3b620dc3a794b5a0005cf71e

Author: bnham

React/Executors/RCTJSCWrapper.mm

@@ -21,7 +21,7 @@
   static dispatch_once_t token;
   static void *handler;
   dispatch_once(&token, ^{
-    handler = dlopen("@executable_path/Frameworks/JavaScriptCore.framework/JavaScriptCore", RTLD_LAZY);
+    handler = dlopen("@executable_path/Frameworks/JavaScriptCore.framework/JavaScriptCore", RTLD_LAZY | RTLD_LOCAL);
     if (!handler) {
       const char *err = dlerror();