i hate gnome

fixes the childwindow hack for gnome/mutter by starting the recursive
search from the desktop HWND instead of the game HWND. i have basically
zero idea why only mutter has the issue where the editor class is neither
a sibling nor a descendant of the main game window, the only thing i can
think of is it's because of some mutter-specific hack that proton does.

patches/wine/0005-osu/0003-winex11-Improved-osu-childwindow-hack-PROTON.patch

@@ -85,7 +85,7 @@ index 0c3c81bcda6..68c623e008c 100644
 -    return (!no_child_clipping_cached && NtUserGetWindowRelative( hwnd, GW_CHILD )) || NtUserGetAncestor( hwnd, GA_PARENT ) != NtUserGetDesktopWindow();
 +static BOOL drawable_needs_clipping( HWND hwnd, BOOL known_child )
 +{
-+    if (!use_osu_child_hack() || editor_visible( hwnd ))
++    if (!use_osu_child_hack() || editor_visible( NtUserGetDesktopWindow() ))
 +    {
 +        if (NtUserGetAncestor( hwnd, GA_PARENT ) != NtUserGetDesktopWindow()) return TRUE; /* child window, needs compositing */
 +        if (NtUserGetWindowRelative( hwnd, GW_CHILD )) return TRUE; /* window has children, needs compositing */