libc: Deglob reexports. #11870

The removes all the glob reexports from liblibc. I did it by removing them all, and then adding back per-platform explicit reexports until everything built again.

I realize this isn't the best strategy for determining an API, but this is the lowest-impact change that solves the problem, plus I'm dissatisfied with the design of this library for other reasons and think it needs to be reconsidered from top to bottom (later).