Fix JACK MIDI dropping events when two events have the same time stamp.

[softrabbit]

As reported and debugged on Discord: JACK MIDI input has a tendency to drop events.
Explanation:

• jack_midi_event_get is called to get a new event at the end of the for loop, if in_event_time == i
• i gets incremented for the next iteration.
• If the newly fetched event has the same time as the previous one, the comparison will be false and remain so for the rest of the buffer. Any further events will be ignored.

I suggest turning the if into a while to handle all events with the same timevalue.

[LmmsBot]

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Windows

• Windows 32-bit: lmms-1.3.0-alpha.1.102%2Bgaa4989bc5-mingw-win32.exe (build link)
• Windows 64-bit: lmms-1.3.0-alpha.1.102%2Bgaa4989bc5-mingw-win64.exe (build link)
• Windows 32-bit: lmms-1.3.0-alpha-msvc2017-win32.exe (build link)
• Windows 64-bit: lmms-1.3.0-alpha-msvc2017-win64.exe (build link)

Linux

• Linux (AppImage): lmms-1.3.0-alpha.1.102%2Bgaa4989b-linux-x86_64.AppImage (build link)

macOS

• macOS : lmms-1.3.0-alpha.1.102%2Bgaa4989bc5-mac10.14.dmg (build link)

🤖

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[VOID404]

As the person reporting the bug, I cannot reproduce it on this version

[Veratil]

@JohannesLorenz you're the previous committer for this loop fixing another bug, so pinging you for attention (would hate to regress). I see no issue changing if to while though. So approval from me. Would like your thumbs up, too.

[softrabbit]

Looking at the function around the fix, I wonder if it could be straightened into a while(jack_midi_event_get(&in_event, port_buf, event_index++) ).

[Veratil]

Tangential topic: I did some looking around, it's possible we may have another bug in this loop related to SysEx messages.
jackaudio/jack2@b744332

[softrabbit]

Tangential topic: I did some looking around, it's possible we may have another bug in this loop related to SysEx messages.
jackaudio/jack2@b744332

MidiClientRaw::parseData which handles the bytes will most likely just ignore the SysEx, so I think we're safe on that point.

[JohannesLorenz]

Sorry, I missed this, but it looks basically good 👍