[X86] Add support for __builtin_cpu_init

This adds builtin_cpu_init which will emit a call to cpu_indicator_init in libgcc or compiler-rt.

This is needed to support builtin_cpu_supports/builtin_cpu_is in an ifunc resolver.

Differential Revision: https://reviews.llvm.org/D36336

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@311874 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed