Merged requested to merge vanvugt/mutter:really_use_clipped_redraw into master
I noticed my system would fall back to the slow unclipped (and
uncullable) paint path whenever a window touched the left edge of
the screen. Turns out that was a red herring. Just that
use_clipped_redraw was uninitialized so clipping/culling was used
So the compiler failed to notice
use_clipped_redraw was uninitialized.
Weirdly, as soon as you fix that it starts complaining that
might be uninitialized, which appears to be wrong. So we initialize that
too, to shut up the compiler warnings/errors.