mlt7: replace deprecated mlt_sample_calculator()

Related to #991

src/jobs/audiothumbjob.cpp

@@ -90,7 +90,7 @@ bool AudioThumbJob::computeWithMlt()
         }
         QScopedPointer<Mlt::Frame> mltFrame(audioProducer->get_frame());
         if ((mltFrame != nullptr) && mltFrame->is_valid() && (mltFrame->get_int("test_audio") == 0)) {
-            int samples = mlt_sample_calculator(float(framesPerSecond), m_frequency, z);
+            int samples = mlt_audio_calculate_frame_samples(float(framesPerSecond), m_frequency, z);
             mltFrame->get_audio(audioFormat, m_frequency, m_channels, samples);
             for (int channel = 0; channel < m_channels; ++channel) {
                 double lev = mltFrame->get_double(keys.at(channel).toUtf8().constData());

src/lib/audio/audioEnvelope.cpp

@@ -113,7 +113,7 @@ AudioEnvelope::AudioSummary AudioEnvelope::loadAndNormalizeEnvelope() const
     for (size_t i = 0; i < max; ++i) {
         std::unique_ptr<Mlt::Frame> frame(m_producer->get_frame(int(i)));
         qint64 position = mlt_frame_get_position(frame->get_frame());
-        int samples = mlt_sample_calculator(float(m_producer->get_fps()), samplingRate, position);
+        int samples = mlt_audio_calculate_frame_samples(float(m_producer->get_fps()), samplingRate, position);
         auto *data = static_cast<qint16 *>(frame->get_audio(format_s16, samplingRate, channels, samples));
 
         summary.audioAmplitudes[i] = 0;