intel-gpu-tools: Build tests needing cairo if ANDROID_HAS_CAIRO=1

intel-gpu-tools: Build tests needing cairo if ANDROID_HAS_CAIRO=1

Until now the tests that depended on libcairo were simply
skipped in the android build. Now that I have a cairo port
working, build these cairo dependent tests if ANDROID_HAS_CAIRO
is set to 1 in the environment.
For information on building cairo for IGT on Android see the
wiki at:

https://securewiki.ith.intel.com/display/GFXCore/IGT+Test+Suite+on+Android

Signed-off-by: Tim Gore <tim.gore@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>