SoftAAC2: fix crash on all-zero adts buffer

Bug: 29153599
Change-Id: I1cb81c054098b86cf24f024f8479909ca7bc85a6

SoftAAC2::~SoftAAC2() {
    aacDecoder_Close(mAACDecoder);
 delete[] mOutputDelayRingBuffer;
}

SoftAAC2::~SoftAAC2() {
    aacDecoder_Close(mAACDecoder);
 delete[] mOutputDelayRingBuffer;
}
