video/out/w32_common: don't move window if position isn't set

The geometry output of vo_calc_window_geometry does not have
any information about the current window position. This causes
the window to move when setting geometry even without setting
x/y.

Change it so that the window position is unchanged if x/y are not
set and after startup.

video/out/w32_common.c

@@ -1944,8 +1944,13 @@ static void window_reconfig(struct vo_w32_state *w32, bool force)
     w32->o_dheight = vo->dheight;
 
     if (!w32->parent && (!w32->window_bounds_initialized || force)) {
-        SetRect(&w32->windowrc, geo.win.x0, geo.win.y0,
-                geo.win.x0 + vo->dwidth, geo.win.y0 + vo->dheight);
+        int x0 = geo.win.x0;
+        int y0 = geo.win.y0;
+        if (!w32->opts->geometry.xy_valid && w32->window_bounds_initialized) {
+            x0 = w32->windowrc.left;
+            y0 = w32->windowrc.top;
+        }
+        SetRect(&w32->windowrc, x0, y0, x0 + vo->dwidth, y0 + vo->dheight);
         w32->prev_windowrc = w32->windowrc;
         w32->window_bounds_initialized = true;
         w32->win_force_pos = geo.flags & VO_WIN_FORCE_POS;