[x86/slh] Add unwind info to several tests to make it more obvious that

we aren't incorrectly generating any of it when doing SLH.

There was a bug that only occured with SLH that very much looked like it
could be caused by bad unwind info, and so this was a prime suspect.
Turns out that everything is fine, but this way we'll *see* if we end
up, for example, putting things we shouldn't inside the prolog.

llvm-svn: 338480