vda: fix build on OS X 10.7

Looks like on 10.8 OpenGL.h recursively includes CGLIOSurface.h. That is not
the case for 10.7 so the build was broken on that version of OS X.

video/out/gl_hwdec_vda.c

@@ -20,6 +20,7 @@
 #include <IOSurface/IOSurface.h>
 #include <CoreVideo/CoreVideo.h>
 #include <OpenGL/OpenGL.h>
+#include <OpenGL/CGLIOSurface.h>
 
 #include "video/decode/dec_video.h"
 #include "cocoa_common.h"

video/out/vo_corevideo.c

@@ -25,6 +25,7 @@
 #include <QuartzCore/QuartzCore.h>
 #if HAVE_VDA_HWACCEL
 #include <IOSurface/IOSurface.h>
+#include <OpenGL/CGLIOSurface.h>
 #endif
 
 #include <assert.h>