Finished Gossip Block Validation Conditions (#2640)

* Gossip Block Validation is Much More Efficient

Co-authored-by: realbigsean <seananderson33@gmail.com>

common/slot_clock/src/system_time_slot_clock.rs

@@ -61,6 +61,10 @@ impl SlotClock for SystemTimeSlotClock {
     fn genesis_slot(&self) -> Slot {
         self.clock.genesis_slot()
     }
+
+    fn genesis_duration(&self) -> Duration {
+        *self.clock.genesis_duration()
+    }
 }
 
 #[cfg(test)]