Only include Xv headers if server supports it

Signed-off-by: Yaakov Selkowitz <yselkowitz@users.sourceforge.net>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>

src/dummy.h

@@ -5,8 +5,10 @@
 
 #include "xf86Cursor.h"
 
+#ifdef XvExtension
 #include "xf86xv.h"
 #include <X11/extensions/Xv.h>
+#endif
 #include <string.h>
 
 /* Supported chipsets */
@@ -57,7 +59,9 @@ typedef struct dummyRec
 
     Bool screenSaver;
     Bool video;
+#ifdef XvExtension
     XF86VideoAdaptorPtr overlayAdaptor;
+#endif
     int overlay;
     int overlay_offset;
     int videoKey;

src/dummy_driver.c

@@ -32,8 +32,10 @@
 
 #include "picturestr.h"
 
+#ifdef XvExtension
 #include "xf86xv.h"
 #include <X11/extensions/Xv.h>
+#endif
 
 /*
  * Driver data structures.