aacdec: fix memory leak at onStop()

onStop() may invoke initDecoder() which could reallocate output ring
buffer without releasing the existing one.

Bug: 196484690
Test: cts/media/device-small
Change-Id: I245aaf2a3c2d471e02befbd67fbe30e54ac8967a
diff --git a/media/codec2/components/aac/C2SoftAacDec.h b/media/codec2/components/aac/C2SoftAacDec.h
index 986187c..a03fc70 100644
--- a/media/codec2/components/aac/C2SoftAacDec.h
+++ b/media/codec2/components/aac/C2SoftAacDec.h
@@ -93,7 +93,7 @@
     bool mEndOfOutput;
     int32_t mOutputDelayCompensated;
     int32_t mOutputDelayRingBufferSize;
-    short *mOutputDelayRingBuffer;
+    std::unique_ptr<short[]> mOutputDelayRingBuffer;
     int32_t mOutputDelayRingBufferWritePos;
     int32_t mOutputDelayRingBufferReadPos;
     int32_t mOutputDelayRingBufferFilled;