rogue3, rogue5: fix all GCC5 warnings.

GCC5 enables more warnings by default, including pre-ANSI implicit
function definitions.  These two games now build cleanly, but the others
will require more effort.

rogue3/main.c

@@ -25,9 +25,8 @@ WINDOW *mw;                              /* Used to store mosnters */
 FILE   *scoreboard = NULL;
 FILE   *logfi = NULL;
 
-main(argc, argv, envp)
-char **argv;
-char **envp;
+int
+main(int argc, char *argv[], char *envp[])
 {
     char *env;
     struct linked_list *item;

rogue5/pack.c

@@ -21,8 +21,8 @@
  *      If this was the object of something's desire, that monster will
  *      get mad and run at the hero
  */
-update_mdest(obj)
-register THING *obj;
+void
+update_mdest(THING *obj)
 {
     register THING *mp;