clutter/stage-view: Bring back sysprof mark for the whole stage update
The "Update" sysprof mark was accidentally removed with commit a9a9a0d1. That mark was useful for profiling the impact of changes influencing multiple phases (like layout and paint) of the stage update though, so bring that mark back.
Since we now update every stage view individually, also change the mark name slightly to "Update view".
Note that measurements using the old "Update" mark can't be compared to measurements using results this one, that's because (besides the mark being per-stage-view now) it also includes the execution time of Clutters PRE_PAINT and POST_PAINT repaint functions.