tests: Skip buffer count test if wl_drm isn't present

This skips the test when running on the headless backend.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
(Presumably) Reviewed-by: Daniel Stone <daniel@fooishbar.org>
diff --git a/tests/weston-test-client-helper.h b/tests/weston-test-client-helper.h
index 2cf3d8f..a6ea524 100644
--- a/tests/weston-test-client-helper.h
+++ b/tests/weston-test-client-helper.h
@@ -26,6 +26,7 @@
 #include "config.h"
 
 #include <assert.h>
+#include <stdbool.h>
 #include "weston-test-runner.h"
 #include "wayland-test-client-protocol.h"
 
@@ -40,6 +41,7 @@
 	struct surface *surface;
 	int has_argb;
 	struct wl_list global_list;
+	bool has_wl_drm;
 };
 
 struct global {