post_distupgrade_exceptions: handle libdb4.8

libdb4.8/squeeze is part of the minimal squeeze chroot and
remains installed after distupgrade even if it no longer
exists in wheezy
db4.8-util/wheezy Conflicts/Replaces libdb4.8, so ensure it
gets removed from the reference chroot, too

Signed-off-by: Andreas Beckmann <debian@abeckmann.de>
pre_install_exceptions: update lvm2 exception

ganeti/lenny and mini-buildd-bld need this, too

Signed-off-by: Andreas Beckmann <debian@abeckmann.de>
post_setup_squeeze-fake-essential: more packages requiring install-info

there are ia few more packages in squeeze that need a fake-essential install-info

Signed-off-by: Andreas Beckmann <debian@abeckmann.de>