Clang CC1 option "-fnative-half-type"

In r235215, I added support for legalizing f16 type in the IR by promoting operations on f16 to f32 and using f16 <-> f32 conversions on load/store. With some backend patches, this promotion works successfully on ARM, AArch64, X86, X86-64, Mips and Mips64.

Is it reasonable to expose the NativeHalfType LangOption in the command line? Clang already exposes HalfArgsAndReturns langopt as '-fallow_half_arguments_and_returns '.

Please advice.

+llvm-dev hoping for a wider audience

(send to right alias)