fix #5163 Add PortAudio Midi Output

[lasconic]

For 2.2 branch

[Jojo-Schmitz]

How about giving it a try, so it can get tested in the 2.2 nighlies?

[ypresto]

On macOS, building MuseScore requires building huge Qt from source or downloading 3.5GB binary.
I wanna try nightly build!

[Jojo-Schmitz]

Nightly builds for macOS are available on https://ftp.osuosl.org/pub/musescore-nightlies/macosx/, this particular fix though is not in any 2.2 nightly yet though, only in those from master

[lasconic]

You can find nightlies here for MacOS http://prereleases.musescore.org/macosx/nightly/
If you need a small download (it will not contain everything Qt but only what you need), you can get it here http://utils.musescore.org.s3.amazonaws.com/qt-opensource-mac-x64-clang-5.4.2.dmg

[ypresto]

I wanna try nightly build!

Oops, I meant I wanna try this PR as nightly build too 🙇
Anyway thanks for instructions about nightly builds and Qt binary. I'll try it later!

[lasconic]

Since we do have some people willing to test this in 2.2, let's merge it and see how it works out. We can always revert if something goes wrong.

[jurf]

@lasconic, hey, this is failing to build on Flathub, see #3170 (comment).