[llvm] [TailDuplicator] Only duplicate the blocks containing computed gotos (PR #114990)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Please don't link to gcc source code in commit messages.

I think it might make sense to try to pursue a more general solution here... can we simplify the CFG while still keeping the benefit of taildup?  Maybe introduce a fake BB into the CFG or something.  But special-casing indirectbr seems okay short-term.

https://github.com/llvm/llvm-project/pull/114990