include: ssp: fortify <wchar.h>
This includes all of the w*() equivalents to str*()/mem*() implemented
in more or less the same way. For these ones, we'll just use
header-only implementations from the start to stop further cluttering
the libc symbol table.
Reviewed by: markj
Sponsored by: Klara, Inc.
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D45682