The error:
CC  libcelt_dec.o
/src/ffmpeg/libavcodec/libcelt_dec.c: In function 'ff_celt_error_to_averror':
/src/ffmpeg/libavcodec/libcelt_dec.c:44: error: 'ENOTRECOVERABLE' undeclared (first use in this function)
/src/ffmpeg/libavcodec/libcelt_dec.c:44: error: (Each undeclared identifier is reported only once
/src/ffmpeg/libavcodec/libcelt_dec.c:44: error: for each function it appears in.)



The relevant area of libcelt_dec.c:

static int ff_celt_error_to_averror(int err)
{
    switch(err) {
        case CELT_BAD_ARG:          return AVERROR(EINVAL);
#ifdef CELT_BUFFER_TOO_SMALL
        case CELT_BUFFER_TOO_SMALL: return AVERROR(ENOBUFS);
#endif
        case CELT_INTERNAL_ERROR:   return AVERROR(EFAULT);
        case CELT_CORRUPTED_DATA:   return AVERROR_INVALIDDATA;
        case CELT_UNIMPLEMENTED:    return AVERROR(ENOTSUP);
        case CELT_INVALID_STATE:    return AVERROR(ENOTRECOVERABLE);
        case CELT_ALLOC_FAIL:       return AVERROR(ENOMEM);
        default:                    return AVERROR_UNKNOWN;
    }
}