[X86] Use unsigned types for vector arithmetic in intrinsics to avoid undefined behav...

[X86] Use unsigned types for vector arithmetic in intrinsics to avoid undefined behavior for signed integer overflow.

This is really only needed for addition, subtraction, and multiplication, but I did the bitwise ops too for overall consistency. Clang currently doesn't set NSW for signed vector operations so the undefined behavior shouldn't happen today.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@271778 91177308-0d34-0410-b5e6-96231b3b80d8