[llvm-branch-commits] [BranchFolding] Remove redundant branches in landing pads (PR #221602)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/221602

Previously we were not handling the case where we have a series of
landing pad blocks that all end up in the same spot but some of them
contain branches to get there. This left subsequent unconditional
branches in the final output.

Works towards #219628.