[llvm] [BranchFolding] Add an option to tail merge only bbs without successors (PR #101969)

[Vladimir Radosavljevic via llvm-commits]

vladimirradosavljevic wrote:

@wangpc-pp I have added test case.
I'm working on a downstream target and we are not using llvm-testsuite, so I can't pull benchmark numbers. Can this be merged without benchmark numbers?

https://github.com/llvm/llvm-project/pull/101969