Merge changes from topic \'merge_dev_master\' am: 197cdc4 am: b3a0e9f
am: 1d28cfb

* commit '1d28cfb0a64ca6eb7ad1cb18f32e59dc45cf43fc':
  Support building 64-bit windows binaries for Clang.
  Build libclangToolingCore.a for extra host tools.
  Add -fnative-half-arguments-and-returns
  Revert "Handle __fp16 natively if HalfArgsAndReturns langopt is set"

Change-Id: I837149faa4b2dcbf856f51bc0361b9d4c2c9c214