backends: X11: Fix memleak.

Free the array of supported _NET_WM Atoms.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
tests: framework: Finish and rename malloc barriers

Rename malloc barriers to malloc canaries and plug them
into the malloc tracking code, so that they could be enabled
for all malloc() calls.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
tests: core: Add BlitClipped() tests.

Add a few basic BlitClipped tests
+ regression test for a off by one bug I've found today.
(fix is on the way)

Signed-off-by: Cyril Hrubis <metan@ucw.cz>