[SelectionDAG] Add a freeze to ISD::ABS expansion.

I had initially assumed this was the problem with
https://github.com/llvm/llvm-project/issues/55271#issuecomment-1133426243

But it turns out that was a simpler issue. This patch is still
more correct than what we were doing before so figured I'd submit
it anyway.

No test case because I'm not sure how to get an undef around
until expansion.

Looking at the test deltas I wonder if it be valid to combine
(sext_inreg (freeze (aextload X))) -> (freeze (sextload X)).

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D126175