add vo_xv_enable_vsync() to xvmc

it may not be needed but at least it shouldn't hurt to have it.


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@15867 b3059339-0415-0410-9bf9-f77b7e298cf2

libvo/vo_xvmc.c

@@ -585,6 +585,7 @@ found_subpic:
      return -1; // bail out, colorkey setup failed
    }
 
+   vo_xv_enable_vsync();//it won't break anything
 
 //taken from vo_xv
    panscan_init();