[llvm] [SimplifyCFG] Avoid introducing complex phi when removing empty blocks (PR #104887)

[Nikita Popov via llvm-commits]

nikic wrote:

Compile-time: https://llvm-compile-time-tracker.com/compare.php?from=bf68e9047f62c22ca87f9a4a7c59a46b3de06abb&to=c2b97e008d826915ca2d23697e00dec989dd72b1&stat=instructions:u Minor improvement on sqlite3 correlated with code size reduction.

https://github.com/llvm/llvm-project/pull/104887