tests: Include "config.h" as first header

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
diff --git a/tests/event-test.c b/tests/event-test.c
index 980dfaa..b60ad85 100644
--- a/tests/event-test.c
+++ b/tests/event-test.c
@@ -21,6 +21,8 @@
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include "weston-test-client-helper.h"
 
 static void