Performance tweak, only signal if there are threads waiting.

src/main/java/com/zaxxer/hikari/util/ConcurrentBag.java

@@ -189,12 +189,14 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
    {
       bagEntry.setState(STATE_NOT_IN_USE);
       
+      if (waiters.get() != 0) {
+         synchronizer.signal();
+      }
+      
       final List<Object> threadLocalList = threadList.get();
       if (threadLocalList != null) {
          threadLocalList.add(weakThreadLocals ? new WeakReference<>(bagEntry) : bagEntry);
       }
-
-      synchronizer.signal();
    }
 
    /**