[llvm] [InstCombine] Remove one-use restriction on icmp of gep fold (PR #76730)

[Nikita Popov via llvm-commits]

nikic wrote:

Huh, this change had a suspiciously large impact on `clang/Driver/Toolchains/`: https://llvm-compile-time-tracker.com/compare_clang.php?from=b5abaea3c0de605c8145035b21a5ee492883ebd7&to=b1b8a383fcdab007ccd1a5daa08cb33ce7cbc6c0&stat=instructions%3Au&sortBy=interestingness 

https://github.com/llvm/llvm-project/pull/76730