errno for programmer error is ERRNO_PROGRAMMER, not ERRNO_MISC.
Add the #mtree v2.0 header (as standard mandates).
Add mtree's archive_match stubs.

mtree matching is fnmatch(3) based, which is different from gtar. A
different matching operation must take place, so archive_match(3) has to
be adapted.
Implement the pwcache(3) functionality from NetBSD's mtree.
Missed that file from the previous commit (inclusion of getid.c
when pwcache(3) is supported by system).
Add RCSID and include archive_platform.h
Add missing character " for the multi-line string.
Add tags parsing for exclude/include lists.