Reapply r289181 but rename the include guard to avoid
conflict with the one from Darwin.
Allow darwin to provide additional definitions and implementation
specifc values for tgmath.h on Apple platforms.
rdar://problem/19019845
llvm-svn: 298013
Reverts r289181: it's currently breaking modules using simd.h in
10.12 SDK.
This reverts commit 6e73e3464e96a4e00492c24aa790d36e1adb5702.
llvm-svn: 289487
Allow darwin to provide additional definitions and implementation
specifc values for tgmath.h on Apple platforms.
rdar://problem/19019845
llvm-svn: 289181