[libc-commits] [libc] [libc] Add a simple scope_exit wrapper and use it in socket tests (PR #192615)

[Michael Jones via libc-commits]

https://github.com/michaelrj-google approved this pull request.

This seems like a very useful tool, I only have minor organizational questions: Since `scope_exit` seems to be still experimental for C++ would it make more sense to put it in top level `__support` since it's not technically C++ standard yet? Additionally, `scope_exit` should probably have a comment explaining where it's from.

P.S. Not necessary for this PR but after it lands I'd like to use this for FILE related tests as well.

https://github.com/llvm/llvm-project/pull/192615