Fix various overlooked causes of warnings.

GCC5 now produces under 300 lines of warnings, but the remaining ones
will require more complex solutions.

arogue5/rogue.h

@@ -1165,6 +1165,7 @@ void    use_mm(int which);
 char   *vowelstr(char *str);
 void    wait_for(WINDOW *win, char ch);
 struct linked_list *wake_monster(int y, int x);
+void    wanderer(void);
 void    waste_time(void);
 char   *weap_name(struct object *obj);
 void    wear(void);