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/common/sectdamage.c

@@ -88,7 +88,6 @@ sect_damage(struct sctstr *sp, int dam, struct emp_qelem *list)
 int
 sectdamage(struct sctstr *sp, int dam, struct emp_qelem *list)
 {
-    extern double unit_damage;
     struct nstr_item ni;
     struct lndstr land;
     struct plnstr plane;