if !G_THREADS_ENABLED, eat the trailing semicolon with a bogus function

if !G_THREADS_ENABLED, eat the trailing semicolon with a bogus function

Thu Dec 17 04:10:49 1998  Tim Janik  <timj@gtk.org>

        * glib.h (G_LOCK_DECLARE_*): if !G_THREADS_ENABLED, eat the
        trailing semicolon with a bogus function declaration, instead
        of with a bogus variable declarations, so we avoid unused
        variable warnings.