sys-fs/udev: Bumped to v211
net-firewall/ipset: Bump to v6.21.1

ChangeLogs: http://ipset.netfilter.org/changelog.html
sys-fs/udev: Small ebuild fixes

The previous version thrown the following error when pkg_postinst() was
called:

  /var/tmp/portage/sys-fs/udev-211/temp/environment: line 3741: etc/fstab: No such file or directory

This was due to missing "/" due to the use of "${ROOT%/}" by upstream.