Continuation of the fix in commit 00a3c698686f25e193d0311ad25c903f0ad71e8b.
Instead of using a separate flag for the resize process, just
delay the setting of the CLUTTER_ACTOR_SYNC_MATRICES flag on the
stage to the point when we receive a ConfigureNotify event from
X11.
This commit will break the stage embedding into other toolkits.
4f6cc0b25f