xf86drmMode.h: use ANSI C99 arrays

This avoids the use of a GNU-specific extension in public headers. Also
see [1].

[1]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/80#note_707458

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
diff --git a/xf86drmMode.h b/xf86drmMode.h
index 90c3425..c28995a 100644
--- a/xf86drmMode.h
+++ b/xf86drmMode.h
@@ -560,14 +560,14 @@
 
 typedef struct drmModeLesseeList {
 	uint32_t count;
-	uint32_t lessees[0];
+	uint32_t lessees[];
 } drmModeLesseeListRes, *drmModeLesseeListPtr;
 
 extern drmModeLesseeListPtr drmModeListLessees(int fd);
 
 typedef struct drmModeObjectList {
 	uint32_t count;
-	uint32_t objects[0];
+	uint32_t objects[];
 } drmModeObjectListRes, *drmModeObjectListPtr;
 
 extern drmModeObjectListPtr drmModeGetLease(int fd);