Some flag cleanup for the sanitizer runtimes.

This hoists most of the CFLAGS into a common variable. It also adds
detection for -Wno-c99-extensions and uses it to silence a pile of
warnings.

Finally, it switches to the proper flag -rdynamic.

With this, the cmake build is warning free on my bootstrap Linux build.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@162809 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed