[CMake] [darwin] [builtins] Match clang_darwin.mk's compiler flags when building builtin libraries
[CMake] [darwin] [builtins] Match clang_darwin.mk's compiler flags when building builtin libraries

On Darwin we have a very restrictive set of flags used when building the builtins. This change makes CMake match autoconf.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@248523 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt