PR 57261 says that you can use *printf() and *scanf() in a signal handler only if you don't use floating-point data. The
 documentation for some of the functions already have this caveat, and I've added to the others that need it.

The PR then says that it isn't safe to use the wide-character printf() functions in signal handlers. Currently, the docs
 say that swprintf() and vswprintf() are safe to use in signal handlers (with the floating-point caveat). Can anyone 
confirm that you can't use these two functions at all in a signal handler?

Thanks.