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_pipe_crc_basic.c

@@ -31,6 +31,7 @@
 
 #include "drmtest.h"
 #include "igt_debugfs.h"
+#include "igt_kms.h"
 
 typedef struct {
 	struct kmstest_connector_config config;