audio effects: fix heap overflow

Check consistency of effect command reply sizes before
copying to reply address.

Also add null pointer check on reply size.
Also remove unused parameter warning.

Bug: 21953516.
Change-Id: I4cf00c12eaed696af28f3b7613f7e36f47a160c4
(cherry picked from commit 0f714a464d2425afe00d6450535e763131b40844)

int VisualizerLib_Release(effect_handle_t handle) {
 VisualizerContext * pContext = (VisualizerContext *)handle;

    ALOGV("VisualizerLib_Release %p", handle);
 if (pContext == NULL) {
 return -EINVAL;
 }
    pContext->mState = VISUALIZER_STATE_UNINITIALIZED;
 delete pContext;

 return 0;
}

int VisualizerLib_Release(effect_handle_t handle) {
 VisualizerContext * pContext = (VisualizerContext *)handle;

    ALOGV("VisualizerLib_Release %p", handle);
 if (pContext == NULL) {
 return -EINVAL;
 }
    pContext->mState = VISUALIZER_STATE_UNINITIALIZED;
 delete pContext;

 return 0;
}
