Calendar.Timezone: Increase INF_YEAR from 2050 to 2100.

The timezone definitions have started containing years beyond 2050
(eg the Egypt rule set has rules up to year 2055).

Fixes testsuite failures.

lib/modules/Calendar.pmod/Timezone.pmod

@@ -758,7 +758,7 @@ class Runtime_timezone_compiler
 
    // ---
 
-#define INF_YEAR 2050
+#define INF_YEAR 2100
 #define NUL_YEAR 1850
 
 	 int y1=(int)a[0] || NUL_YEAR;