[X86] Remove GCCBuiltins from cvtsi2ss/cvtsi2sd/cvtss2sd intrinsics as they aren't used by clang. Add TODOs to remove these and some other unused intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286091 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed