[WPE] Fix build when EXTERNAL_HOLEPUNCH is enabled

https://bugs.webkit.org/show_bug.cgi?id=294204

Reviewed by Adrian Perez de Castro.

When EXTERNAL_HOLEPUNCH is used, DestinationColorSpace needs to be
included.

* Source/WebCore/platform/graphics/holepunch/MediaPlayerPrivateHolePunch.h:

Canonical link: https://commits.webkit.org/296027@main

Author: spenap

Source/WebCore/platform/graphics/holepunch/MediaPlayerPrivateHolePunch.h

@@ -22,6 +22,7 @@
 
 #if USE(EXTERNAL_HOLEPUNCH)
 
+#include "DestinationColorSpace.h"
 #include "MediaPlayerPrivate.h"
 #include "PlatformLayer.h"
 #include <wtf/RefCounted.h>