[X86] Move the information about the feature bits used by compiler-rt and shared by Host.cpp to a .def file and TargetParser.h so clang can make use of it.

Since we keep Host.cpp and compiler-rt relatively in sync, clang can use this information as a proxy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318814 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed