Revert "Handle __fp16 natively if HalfArgsAndReturns langopt is set"

This reverts commit ba8a5652592440418dad2c5be62710b994c7fe11.

(cherry picked from commit 65ebe08e20e1e45557f00c6382743b3ea4792529)

Change-Id: Id793081c984af69c6b671ab30c94c3d11a55f684
1 file changed