common/DecayCounter: add delta to value for ::get

This resolves a bug where getting the DecayCounter value before one second has
elapsed will result in 0 always being returned. This is because ::hit will add
to the delta, not the value. The delta is added to the value only in the decay
function which only processes changes after 1 second has elapsed since the last
decay.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

src/common/DecayCounter.h

@@ -73,7 +73,7 @@ public:
 
   double get(utime_t now, const DecayRate& rate) {
     decay(now, rate);
-    return val;
+    return val+delta;
   }
 
   double get_last() {