Update build-hermes-xcode.sh to fail faster

[kraenhansen]

Summary:

While debugging an error building hermes from source in a React Native app, I kept getting this weird error:

Building for 'iOS-simulator', but linking in dylib ({redacted}/ios/Pods/hermes-engine/destroot/Library/Frameworks/ios/hermes.framework/hermes) built for 'macOS'

The root cause was a call to cmake failing, but /sdks/hermes-engine/utils/build-hermes-xcode.sh didn't exit on the error and instead continued building the hermes.framework from the dummy frameworks created by ./sdks/hermes-engine/utils/create-dummy-hermes-xcframework.sh.

I suggest fixing this by introducing a set -e call similar to that used in build-hermesc-xcode.sh:

react-native/packages/react-native/sdks/hermes-engine/utils/build-hermesc-xcode.sh

Line 7 in 2f523f0

set -x -e

Changelog:

[Internal] - Ensure building hermes from source exits early on failures

Test Plan:

I followed https://github.com/facebook/hermes/blob/main/doc/ReactNativeIntegration.md getting to a state of building a React Native app with Hermes built from source. I then introduced an error in hermes/API/hermes/hermes.cpp (I simply typed asd in the top of the file) and built the app from Xcode:

If you scroll up, you can see the failed cmake build, but it just continues trying to build the framework, effectively hiding the error:

When applying this patch and cleaning the build folder, the error is more prominent and actionable:

[dmytrorykun]

@kraenhansen thank you for this PR.
Could you please change [IOS] [FIXED] to [Internal].
And also update the test plan with the error messages before and after the change.

[kraenhansen]

I've updated the description and uploaded a few screenshots to illustrate the before and after state of things 🤞