Merged PR 3571: BUG: In single threaded compilation, the trie API did…

… not use the counter structure.

This resulted in a compilation failure when `FIFTYONEDEGREES_NO_THREADING` was defined.
The counter is now used correctly.

src/trie/51Degrees.c

@@ -1778,7 +1778,7 @@ fiftyoneDegreesActiveDataSet* incrementActive(
 		incremented,
 		active) == FALSE);
 #else
-	provider->active->inUse++;
+	provider->active->counter.inUse++;
 	incremented = *provider->active;
 #endif
 	return incremented.self;