lib: Move kms stuff from drmtest.c over to igt_kms.c

This makes cairo dependencies easier to handle. Otherwise, we
would have to litter drmtest all over with "#ifndef ANDROID"

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
[danvet: Add missing _GNU_SOURCE to igt_kms.c and missing include to
intel_sprite_on.c]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/kms_render.c

@@ -36,6 +36,7 @@
 #include "intel_bufmgr.h"
 #include "intel_batchbuffer.h"
 #include "intel_gpu_tools.h"
+#include "igt_kms.h"
 
 drmModeRes *resources;
 int drm_fd;