Fix dependency errors when linking libproc.

Reported by:	Oliver Hartmann
X-MFC-With:	r272488
- Add some tests for modifying groups

Reviewed by:	will
Bump .Dd missed in r271424
Convert racct stubs to inline functions.

This saves some symbols and function calls for kernel without RACCT.

MFC after:	1 week
Merge remote-tracking branch 'freebsd/master' into hardened/current/master