[X86] Use btc/btr/bts to implement xor/and/or that affects a single bit in the upper 32-bits of a 64-bit operation.
We can't fold a large immediate into a 64-bit operation. But if we know we're only operating on a single bit we can use the bit instructions.
For now only do this for optsize.
Differential Revision: https://reviews.llvm.org/D37418