explicitly set autoglob=False on programatically created targets.

Summary:
I'm going to be flipping the default from autoglob on `fb_apple_library` to `True`. This prepares the target so that there are no behavior changes.

## Changelog: [Internal]

Reviewed By: natestedman

Differential Revision: D29769275

fbshipit-source-id: 7ac04f8a8f7e41ce8d43a81b25ebd063b3a9f3de

React/CoreModules/BUCK

@@ -14,6 +14,7 @@ rn_apple_library(
         ],
     ),
     exported_headers = glob(["**/*.h"]),
+    autoglob = False,
     compiler_flags = [
         "-Wno-error=unguarded-availability-new",
         "-Wno-unknown-warning-option",