Use CMAKE_C_COMPILER_ARG1 in compiler invocation

This is needed when using compiler wrappers such as ccache or distcc
and should address the failure on clang-x86_64-debian-fast bot.

Differential Revision: https://reviews.llvm.org/D62104

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@361111 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed