skins(Linux) : fix crash with a few skins (e.g Orangeade) and xcb_x11

On X11, windows are created with a 1x1 size and updated later on.
In some context, vout_display can catch this 1x1 size before the size is updated.
This results in a crash in swcaler.c which gets a 1x0 size (division by zero)
Changing default to 10x10 solves the problem.

modules/gui/skins2/x11/x11_window.cpp

@@ -88,7 +88,7 @@ X11Window::X11Window( intf_thread_t *pIntf, GenericWindow &rWindow,
     }
 
     // Create the window
-    m_wnd = XCreateWindow( XDISPLAY, m_wnd_parent, -10, 0, 1, 1, 0, 0,
+    m_wnd = XCreateWindow( XDISPLAY, m_wnd_parent, -10, 0, 10, 10, 0, 0,
                            InputOutput, CopyFromParent, valuemask, &attr );
 
     // wait for X server to process the previous commands