[cmake] Work around -Wunused-driver-argument warnings

Fix the Darwin logic so that -msse3 is only used on macOS, and
-fomit-frame-pointer is not used on armv7/armv7k/armv7s.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@312390 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed