[X86] [PATCH] [intrinsics] Lowering X86 ABS intrinsics to IR. (clang)

[X86] [PATCH] [intrinsics] Lowering X86 ABS intrinsics to IR. (clang)

This patch, together with a matching llvm patch (https://reviews.llvm.org/D37693), implements the lowering of X86 ABS intrinsics to IR.

Differential Revision: https://reviews.llvm.org/D37694

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@313133 91177308-0d34-0410-b5e6-96231b3b80d8