[llvm] [SelectionDAG] Freeze dynamic vector indices lowered through the stack (PR #225031)

[Mahmoud Naderi via llvm-commits]

slant14 wrote:

@XChy Are the changes according to what you asked for? Also can you please re-run the linux build job? It seems there is a timeout, and it doesn't seems to be triggered but the SelectionDAG tests.

https://github.com/llvm/llvm-project/pull/225031