tests: Cleanup superfluous headers

Mostly remove headers that aren't actually needed for anything.
Add stdint.h to permit dropping xf86drm.h, which is otherwise unneeded.

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Acked-by: Marek Chalupa <mchqwerty@gmail.com>
Tested-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/tests/buffer-count-test.c b/tests/buffer-count-test.c
index 8b1dd5d..5985a9e 100644
--- a/tests/buffer-count-test.c
+++ b/tests/buffer-count-test.c
@@ -23,16 +23,13 @@
 #include "config.h"
 
 #include <string.h>
-
-#include "weston-test-client-helper.h"
 #include <stdio.h>
-#include <poll.h>
-#include <time.h>
-
 #include <EGL/egl.h>
 #include <wayland-egl.h>
 #include <GLES2/gl2.h>
 
+#include "weston-test-client-helper.h"
+
 #define fail(msg) { fprintf(stderr, "%s failed\n", msg); return -1; }
 
 struct test_data {