Log Message:
update to 2.20.0
This switches to the new gnome-2.20 branch.

pkgsrc notes:
-System dependant parts were reorganized upstream, in particular there
 if a subtree for FreeBSD now, and one for the other BSDs. I didn't
 pull in the DragonFly patches because I can't decide whether to base
 them on the freebsd or the rest.
-I've changed the NetBSD code to use kinfo_proc2 almost completely.
 Some vm statistics reporting might be less accurate now because
 some fields in proc2 seem to be unmaintained by the current kernel
 (eg ixrss).
-Also, some libgtop functions might be able to run in the non-privileged
 part now, but dealing with this would require even more #ifdefs, so
 we should consider setting up a private subtree as FreeBSD did.
-I didn't verify with older NetBSDs; kvm_getproc2() has been in the
 tree for quite some time so I hope it will just work without the need
 for excessive "#if __NetBSD_Version__ > t".