Merge "surfaceflinger_client: Don't dereference NULL ptrs."

        // e.g. if GraphicBuffer is used to wrap an android_native_buffer_t that

        // was dequeued from an ANativeWindow.

        for (size_t i = 0; i < mBuffers.size(); i++) {

            if (buffer->handle == mBuffers[i]->handle) {

            if (mBuffers[i] != 0 && buffer->handle == mBuffers[i]->handle) {

                idx = mBuffers[i]->getIndex();

                break;

            }