wmaker: removed dead code related to 'GLOBAL_SUBMENU_FILE'
There was the possibility to include a global sub-menu to the root menu
using a dedicated file, but this does not look like it is really useful as
this root menu is already defined by a user file, and the root menu is
already specific enough that it does not need anything more 'global'.
Furthermore, the variable enabling this feature (GLOBAL_SUBMENU_FILE) is
not defined anywhere (neither from "configure", nor in "wconfig.h", ...) and
is also not documented at all.
Considering it was introduced a very long time ago (1999!) and was not
touched anymore, this patch removes the dead code associated with it.
Signed-off-by: Christophe CURIS <christophe.curis@free.fr>