[PATCHES] services dropping privs and not linking to libc

[David van Moolenbroek]

A bunch of related patches that together achieve the following:

- PFS drops its root privileges upon startup, as before;
- the printf output of inet and isofs is visible again;
- no services are left that need to be linked against libc (instead of libminc).

The details are not too pretty, but it should be an overall improvement.

http://gerrit.minix3.org/#/c/2998/ - VFS: during initial mount, receive but block work
http://gerrit.minix3.org/#/c/2999/ - PFS, inet: use static UID to drop privileges
http://gerrit.minix3.org/#/c/3000/ - inet: do not link against libc
http://gerrit.minix3.org/#/c/3001/ - isofs: do not link against libc

David