tests: Convert 'xalloc's to 'zalloc's
tests: Convert 'xalloc's to 'zalloc's

xalloc terminates the program abruptly if the requested amount of
memory couldn't be allocated. To insure that the errors are handled
cleanly, use zalloc instead.

Signed-off-by: Seedo Eldho Paul <0425fe44e96d74a5a033dcbb43c4d327c8c74936@gmail.com>
Acked-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>
Reviewed-by: Bryce Harrington <bdb14cfc1ab8d24e13de84adc40b41ae60c13bd1@osg.samsung.com>

Fantu/compositor-spice,sir-murray/weston,krezovic/weston,Fantu/compositor-spice,udoprog/weston,krezovic/weston,giucam/weston,Gnurou/weston,giucam/weston,udoprog/weston,Gnurou/weston,kwm81/weston,Fantu/compositor-spice,kwm81/weston,sir-murray/weston