[InstCombine] prevent miscompiles from select-of-div/rem transform

This avoids the danger shown in issue #60906.
There were no regression tests for these patterns, so these potential
failures have been around for a long time.

We freeze the condition and preserve the optimization because
getting rid of a div/rem is always a win.

Here are a couple of examples that can be corrected by freezing the
condition:
https://alive2.llvm.org/ce/z/sXHTTC

Differential Revision: https://reviews.llvm.org/D144671