[compiler-rt] r233215 - On OS X, explicitly use libc++

[Kuba Brecka]

> ASan requiring 10.7 is fine for us.
> 
> The problem is that we're only doing a single build of Clang and
> compiler-rt, and we use that for both non-asan and asan builds of
> Chrome. If I build compiler-rt with MACOSX_DEPLOYMENT_TARGET=10.7, are
> you saying that the non-asan parts of compiler-rt will still work on
> 10.6 machines? Because that's all I need.
> 
> Apologies for the confusion here. I don't really know much about
> compiler-rt or Mac.

I think you should be fine with what you suggested before, i.e. not setting MACOSX_DEPLOYMENT_TARGET at all.  ASan will get built with support for 10.7+ no matter what your OS version is.  The non-sanitizer parts (builtins) only build into a .a archive, so the deployment target doesn’t (shouldn’t) matter here.

Kuba