wayland: Don't freeze the frame clock too early

wayland: Don't freeze the frame clock too early

We can't freeze the frame clock on commit, but only after-paint,
otherwise the frameclock will resume in the paint stage.

So freeze the frame clock at the end of the frame if we are waiting for
a frame callback.

Note; The diff is only lage because of indentation changes due to
avoiding early returns in favor of a branch.