Add --min-cache-ttl option.

src/config.h

@@ -27,6 +27,7 @@
 #define RANDOM_SOCKS 64 /* max simultaneous random ports */
 #define LEASE_RETRY 60 /* on error, retry writing leasefile after LEASE_RETRY seconds */
 #define CACHESIZ 150 /* default cache size */
+#define TTL_FLOOR_LIMIT 3600 /* don't allow --min-cache-ttl to raise TTL above this under any circumstances */
 #define MAXLEASES 1000 /* maximum number of DHCP leases */
 #define PING_WAIT 3 /* wait for ping address-in-use test */
 #define PING_CACHE_TIME 30 /* Ping test assumed to be valid this long. */