added timer for maxed calculation time.

lceb.h

@@ -7,6 +7,9 @@
 #define MAX(a,b)        (((a)>(b))?(a):(b))
 #define ABS(a)          (((a)<0)?-(a):(a))
 
+#define NANOSEC    1000000000.0
+#define MILLISEC   1000
+
 typedef enum {
     Nop='N',
     Add='+',
@@ -71,6 +74,7 @@ extern void print_results();
 /* signal.c */
 extern void set_intr();
 extern int stopped();
+extern void set_alarm(int ms);
 
 /* tree.c */
 extern NODE *get_node();