avformat/rtmppkt: Check for packet size mismatches

Fixes out of array access

Found-by: Paul Cher <paulcher@icloud.com>
Reviewed-by: Paul Cher <paulcher@icloud.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
static const char* rtmp_packet_type(int type)
{
    switch (type) {
    case RTMP_PT_CHUNK_SIZE:     return "chunk size";
    case RTMP_PT_BYTES_READ:     return "bytes read";
    case RTMP_PT_PING:           return "ping";
    case RTMP_PT_SERVER_BW:      return "server bandwidth";
    case RTMP_PT_CLIENT_BW:      return "client bandwidth";
    case RTMP_PT_AUDIO:          return "audio packet";
    case RTMP_PT_VIDEO:          return "video packet";
    case RTMP_PT_FLEX_STREAM:    return "Flex shared stream";
    case RTMP_PT_FLEX_OBJECT:    return "Flex shared object";
    case RTMP_PT_FLEX_MESSAGE:   return "Flex shared message";
    case RTMP_PT_NOTIFY:         return "notification";
    case RTMP_PT_SHARED_OBJ:     return "shared object";
    case RTMP_PT_INVOKE:         return "invoke";
    case RTMP_PT_METADATA:       return "metadata";
    default:                     return "unknown";
    }
}

static const char* rtmp_packet_type(int type)
{
    switch (type) {
    case RTMP_PT_CHUNK_SIZE:     return "chunk size";
    case RTMP_PT_BYTES_READ:     return "bytes read";
    case RTMP_PT_PING:           return "ping";
    case RTMP_PT_SERVER_BW:      return "server bandwidth";
    case RTMP_PT_CLIENT_BW:      return "client bandwidth";
    case RTMP_PT_AUDIO:          return "audio packet";
    case RTMP_PT_VIDEO:          return "video packet";
    case RTMP_PT_FLEX_STREAM:    return "Flex shared stream";
    case RTMP_PT_FLEX_OBJECT:    return "Flex shared object";
    case RTMP_PT_FLEX_MESSAGE:   return "Flex shared message";
    case RTMP_PT_NOTIFY:         return "notification";
    case RTMP_PT_SHARED_OBJ:     return "shared object";
    case RTMP_PT_INVOKE:         return "invoke";
    case RTMP_PT_METADATA:       return "metadata";
    default:                     return "unknown";
    }
}
