Features: Only require AppleClang policy to be NEW on APPLE.
Features: Use the features symbol in the feature-test compile.

Clang discards the entire string if it is not used, removing
the ability to read the features from the compiled binary. That
is prevented by using the symbol.
Merge topic 'minor-cleanups' into next

92059813 Features: Use the features symbol in the feature-test compile.
5c04dfe4 Features: Only require AppleClang policy to be NEW on APPLE.
Extend release notes.
Merge topic 'compile-features-C-language' into next

2ea825ad Extend release notes.