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.

include/decl.h

@@ -1131,7 +1131,6 @@ struct instance_globals {
     /* restore.c */
     int n_ids_mapped;
     struct bucket *id_map;
-    boolean restoring;
     struct fruit *oldfruit;
     long omoves;