[RFC] Replace vim_strncpy with strlcpy

I'm thinking we should take this course of action:

1. Leave out the DLOG/WLOG for now
2. Create another issue/PR with as a first commit the WLOG/DLOG statements.
3. Track down improper usage of `xstrlcpy`, replace with `mem(p)cpy`/`stracpy`/... as required
4. Remove the WLOG/DLOG commit
5. mark RDY

That means we at least have it ongoing but we don't have a lot of logspam in the regular build. What do you think @dougschneider and @philix?