Fix build error due to drm.h: 'size_t unknown type'

--- cogl/winsys/cogl-winsys-egl-kms.c.orig	2013-10-20 06:58:32.967367785 +0200
+++ cogl/winsys/cogl-winsys-egl-kms.c	2013-10-20 06:58:44.326456462 +0200
@@ -32,6 +32,7 @@
 #include "config.h"
 #endif
 
+#include <sys/types.h>
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <drm.h>