These routines provide test cases an ability to capture screen images
for rendering verification.
This commit is a no-change refactoring, except for making the routines
non-static. Makefile rules are also updated; most notably, this links
test clients against the cairo libraries now.
v2: Fix pointer code styling, suggested in review
Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>