codecs: check OMX buffer size before use in (gsm|g711)dec

Bug: 27793163
Bug: 27793367
Change-Id: Iec3de8a237ee2379d87a8371c13e543878c6652c

SoftGSM::~SoftGSM() {
    gsm_destroy(mGsm);
}

SoftGSM::~SoftGSM() {
    gsm_destroy(mGsm);
}
