[c] Apply left over time additively to track time of delayed TrackEntry. See #1504.

spine-c/spine-c/src/spine/AnimationState.c

@@ -280,7 +280,7 @@ void spAnimationState_update (spAnimationState* self, float delta) {
 			float nextTime = current->trackLast - next->delay;
 			if (nextTime >= 0) {
 				next->delay = 0;
-				next->trackTime = current->timeScale == 0 ? 0 : (nextTime / current->timeScale + delta) * next->timeScale;
+				next->trackTime += current->timeScale == 0 ? 0 : (nextTime / current->timeScale + delta) * next->timeScale;
 				current->trackTime += currentDelta;
 				_spAnimationState_setCurrent(self, i, next, 1);
 				while (next->mixingFrom) {