unused variable: g.restoring

Get rid of the last reference to 'g.restoring' (which managed to
unintentionally survive the change to 'g.program_state.restoring').

Also have suppress_map_output() check 'g.program_state.saving' and
switch the couple of checks against that flag to use the function.

src/decl.c

@@ -580,7 +580,6 @@ const struct instance_globals g_init = {
     /* restore.c */
     0, /* n_ids_mapped */
     0, /* id_map */
-    FALSE, /* restoring */
     UNDEFINED_PTR, /* oldfruit */
     UNDEFINED_VALUE, /* omoves */