[llvm] [MergeICmps] Fix miss-compile in MergeICmps in presence of blockaddresses (PR #145925)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM. Strictly speaking we should be checking for an indirectbr predecessor, but address taken is close enough.

https://github.com/llvm/llvm-project/pull/145925