multimedia/qmmp-qt5: unbreak with ffmpeg 4.0

src/plugins/Input/ffmpeg/decoder_ffmpeg.h:64:43: error: use of undeclared identifier 'FF_INPUT_BUFFER_PADDING_SIZE'

uchar m_input_buf[INPUT_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
                                      ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:37:17: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

return (int)d->input()->read((char*)buf, size);
            ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:49:16: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

return d->input()->size();
       ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:54:24: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

absolute_pos = d->input()->pos() + offset;
               ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:57:24: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

absolute_pos = d->input()->size() - offset;
               ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:62:43: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

if(absolute_pos < 0 || absolute_pos > d->input()->size())
                                      ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:64:12: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

return d->input()->seek(absolute_pos);
       ^

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:131:19: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

pd.buf_size = input()->peek((char*)buf, sizeof(buf) - AVPROBE_PADDING_SIZE);
              ^~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:153:27: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

m_stream->seekable = !input()->isSequential();
                      ^~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:166:9: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

if (input()->isSequential())
    ^~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:204:9: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

addMetaData(metaData);
^~~~~~~~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:209:5: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

setReplayGainInfo(rg.replayGainInfo());
^~~~~~~~~~~~~~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:271:19: error: cannot initialize object parameter of type 'Decoder' with an expression of type 'DecoderFFmpeg'

m_totalTime = input()->isSequential() ? 0 : ic->duration * 1000 / AV_TIME_BASE;
              ^~~~~

src/plugins/Input/ffmpeg/decoder_ffmpeg.cpp:301:5: error: no matching member function for call to 'configure'

configure(c->sample_rate, m_channels, format);
^~~~~~~~~

src/plugins/Input/ffmpeg/../../../qmmp/decoder.h:177:10: note: candidate function not viable: no known conversion from 'DecoderFFmpeg' to 'Decoder' for object argument

void configure(quint32 srate, int channels, Qmmp::AudioFormat f = Qmmp::PCM_S16LE);
     ^

src/plugins/Input/ffmpeg/../../../qmmp/decoder.h:170:10: note: candidate function not viable: no known conversion from 'DecoderFFmpeg' to 'Decoder' for object argument

void configure(quint32 srate, const ChannelMap &map, Qmmp::AudioFormat f = Qmmp::PCM_S16LE);
     ^

src/plugins/Input/ffmpeg/../../../qmmp/decoder.h:182:10: note: candidate function not viable: requires single argument 'p', but 3 arguments were provided

void configure(const AudioParameters &p);
     ^

PR: 227726
Reported by: antoine (via exp-run)