fix: broken Hermes.podspec post-install in release (#364)

Summary:
Utilities are not part of a final package. We need to check for their presence while Hermes is being installed, otherwise, this will throw an error and make installation impossible.

Pull Request resolved: #364

Reviewed By: tmikov

Differential Revision: D23817638

Pulled By: dulinriley

fbshipit-source-id: 8e793cc0341925f08e9bf40a285e57b64d8b12ff

hermes.podspec

@@ -36,6 +36,12 @@ Pod::Spec.new do |spec|
     # See `build-apple-framework.sh` for details
     DEBUG=#{HermesHelper::BUILD_TYPE == :debug}
 
+    # In a release package, there are no utilities and source files, we exit
+    # early as there is nothing to build 
+    if [ ! -f ./utils/build-apple-framework.sh ]; then
+      exit 0;
+    fi
+
     # Source utilities into the scope
     . ./utils/build-apple-framework.sh