Declare all configuration variables in optlist.h. Include that

instead of declaring them all over the place.  This uncovered type
errors:
(s_p_etu, adj_update): Defined long, sometimes declared int.  Kills
big endian machines where sizeof(long) != sizeof(int).  Change to
int.

(set_option, delete_option, optstrset, intset, floatset, doubleset,
longset, optionset, optiondel, worldxset): Change linkage to static.

src/lib/commands/prod.c

@@ -68,8 +68,6 @@ count_pop(register int n)
 int
 prod(void)
 {
-    extern double obrate, uwbrate;
-    extern int etu_per_update;
     struct natstr *natp;
     struct sctstr sect;
     struct nstr_sect nstr;