Fix X11 and QPA compilation problems

The X11 buffer pool was using outdated APIs, and as the 'qpa'
configuration value is being removed, it caused the X11 code
to be pulled in, and therefore cause compilation failures.

Change-Id: I5fdaed854c6525716fccca44b5fbd0b850880cb9
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/plugins/gstreamer/qx11videosurface.h

@@ -45,8 +45,6 @@
 #include <QtWidgets/qwidget.h>
 #include <qabstractvideosurface.h>
 
-#ifndef QT_NO_XVIDEO
-
 #include <X11/Xlib.h>
 #include <X11/extensions/Xv.h>
 #include <X11/extensions/Xvlib.h>
@@ -89,7 +87,9 @@ public:
 
     bool present(const QVideoFrame &frame);
 
-private:   
+private:
+    Display *display() const;
+
     WId m_winId;
     XvPortID m_portId;
     GC m_gc;
@@ -114,6 +114,4 @@ private:
 
 QT_END_NAMESPACE
 
-#endif //QT_NO_XVIDEO
-
 #endif