headers: Deduplicate (v)swprintf, (v)snwprintf _(v)swprintf, _(v)scwprintf functions across UCRT/msvcrt builds

All these functions have same ABI and symbol name in all import libraries.
So deduplicate function declarations in stdio.h and wchar.h header files to
have just one declaration not depending on the _UCRT macro.

Signed-off-by: Martin Storsjö <martin@martin.st>
2 files changed