Use pointer comparison for coincident points to ensure a well-defined ordering, and avoid setting discard on both points. This fixes problems with my Mac's implementation of qsort. Final patch by Bertram Felgenhauer.
Update reference images after the change.
CLEAR and SOURCE are now bounded.
Assert that SOURCE and CLEAR aren't passed to these functions.
Assert that SOURCE and CLEAR aren't passed to these functions when there is a mask.
Do fixups for SOURCE and CLEAR as well as unbounded operators, since in the absence of a mask, we need SOURCE to work correctly (don't care about CLEAR)
_cairo_ft_font_show_glyphs) Consistently use CLEAR/TRANSPARENT (source doesn't matter) rather than SOURCE/TRANSPARENT when clearing rectangles.
src/cairo-xlib-surface.c src/cairo-surface.c: Use IN rather than SOURCE as an example of an unbounded operator in docs.
Remove CLEAR/SOURCE columns since they are no longer unbounded.
test/operator-clear.c test/operator-source Makefile.am: Add targetted tests of CLEAR/SOURCE.
