[llvm] Support target names with dots in more utilities (PR #65812)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Just making sure I follow: the problem with `stem` is that if a filename includes a dot, but no ".exe" or equivalent suffix, it would drop the bit from the last dot onwards, even though it might be part of the tool's actual name. Is that correct?

It looks like a number of tools have changed, but I don't see equivalent test changes/new tests for all of them. It seems like we should have testing for all cases where the code goes to some attempt to print the tool name.
Assuming it is, I note that some tools no longer will drop "other" file extensions. However, I don't know of any real such extensions other than Window's ".exe". Do any others exist on other platforms?

https://github.com/llvm/llvm-project/pull/65812