This patch introduces an optional argument to Buffer::updateLabels(), so

This patch introduces an optional argument to Buffer::updateLabels(), so
as to allow us to call the routine when we are preparing for output and
so to do certain things we might not want to do every time.

This is an abuse of updateLabels(), in a way, but updateLabels() long
ago became the general recurse-through-the-Buffer routine, and to
implement the sort of thing I want to do here in validate(), say, much
of the code in updateLabels()---in particular, the counter-update
code---would have to be duplicated. So I believe this is the best, and
easiest, way to go.

Actual use of the new argument will follow.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@32318 a592a061-630c-0410-9148-cb99ea01b6c8