merge.applyupdates: add all actions returned from merge state
At the moment this is a no-op (the only actions defined are 'r', 'a' and 'g'),
but soon we're going to add other sorts of actions to the dictionary returned
from mergestate.actions().
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state