I suggest implementing strlcat and strlcpy, as in OpenBSD. I can write them, but I'm not sure where to place them. They should either be inlined (as in - implemented in an include file as a static func), or in some library that will be linked (statically, I hope). Ideas?
Since the do exists on some platforms (OpenBSD and FreeBSD) the obvious place to put them would be library/port.c like any other function that doesn't exists on all platforms. Just remember to add detect in configure.ac and use the HAVE_ macro in library/port.c
As for (re)writing them. Why not just borrow the source from FreeBSD or OpenBSD. They both have licenses compatible with Wine. No need to reinvent the wheel.