CodeQL fixes, take 2 (#745)

* Protect values against integer overflow

When the code multiplies integer values in an rvalue context before
it's stored in a larger type, the on-the-fly math is stored as int.
The value can overflow before it reaches the wider memory space.

To prevent this, we explicitly cast the result of the arithmetic
to the destination type.

Issues flagged by GitHub CodeQL.

* Apply these fixes correctly

src/FFmpegReader.cpp

@@ -1537,10 +1537,9 @@ void FFmpegReader::ProcessAudioPacket(int64_t requested_frame, int64_t target_fr
 	// Copy audio samples over original samples
 	memcpy(audio_buf,
 	       audio_converted->data[0],
-	       static_cast<size_t>(
-	           audio_converted->nb_samples
+	       static_cast<size_t>(audio_converted->nb_samples)
 	           * av_get_bytes_per_sample(AV_SAMPLE_FMT_S16)
-	           * info.channels)
+	           * info.channels
 	      );
 
 	// Deallocate resample buffer