[llvm] [GVNSink] Fix #77415: GVNSink fails to optimize LLVM IR with debug info (PR #77419)

[Nico Weber via llvm-commits]

nico wrote:

Looks like this breaks tests on windows: http://45.33.8.238/win/88058/step_11.txt

Please take a look and revert for now if it takes a while to fix.

https://github.com/llvm/llvm-project/pull/77419