winex11: Always check if the GL drawable offscreen state needs to be changed. It might change when the window region has changed and requires child window clipping or doesn't anymore. Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57503
winex11: Skip offscreening if the children don't require clipping. Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=57503