[llvm] [SROA] Remove pointer bitcast lookthrough for selects (PR #220199)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM

`bitcast ptr %p to ptr` is technically legal, but it's a no-op.  Pointers can't be bitcast to any other type.  (With byte types, it will be possible to bitcast between a pointer and a byte type, but then the result wouldn't be a pointer.)

https://github.com/llvm/llvm-project/pull/220199