(FALLOUT_MAX): New.

(doland, detonate, spread_fallout): Use it.  With variables, fallout
beyond the capacity of variables (65535) was ignored, except in
doland(), where it saturated at 9999, and spread_fallout, where it
could overflow.  Now it always saturates at FALLOUT_MAX.

include/sect.h

@@ -188,6 +188,8 @@ extern struct dchrstr bigcity_dchr;
 #define CHE_MAX 255
 /* maximum number of mines, must fit into struct sctstr member sct_mines */
 #define MINES_MAX 65535
+/* maximum fallout, must fit into struct sctstr member sct_fallout */
+#define FALLOUT_MAX 9999
 
 /* Each cost is per point of efficency */
 struct sctintrins {