* sysdeps/mach/hurd/dl-sysdep.c (__getcwd): New weak function.
* mach/Versions, hurd/Versions: Add numerous symbols.
Remove libmachuser and libhurduser sections, punt
versioning for those libraries for now.
* misc/Versions: Add reboot here; it exists on all platforms.
* sysdeps/unix/sysv/linux/Versions: Remove reboot here.
