[MU3] Prepare for updated libsndfile

[Jojo-Schmitz]

This enables us to update libsndfile from the currently used 1.0.25 to 1.0.29 or later (1.0.30 is available meanwhile too, see https://github.com/erikd/libsndfile), which apparently changed the name of the lib from libsndfile-1to just sndfile.
In a separate step the dependencies file for Windows may get updated. If the newer one is found on build, that is taken, else the older one.
This in turn might enable us to add opus support, see https://musescore.org/en/node/288994

[Jojo-Schmitz]

Attached the updated dependencies.zip (renamed to dependencies.7z.zip as GitHub doesn't allow .7x).
It has 1.0.29 sndfile.dll and sndfile.lib added for 32-bit and 64-bit, sndfile.h updated and sndfile.hh added.
dependencies.7z, as taken from https://github.com/erikd/libsndfile/releases/tag/v1.0.29

Downloading it does report (in Microsoft Security Essentials/Windows Defender Antivirus) it to be infected with a virus/trojan (Trojan:Script/Wacatac.B!ml), not sure why though? Anyhow, further down I attached a newer version, so we can safely ignore this here.
Edit: that report is gone meanwhile, probably a temp glitch with the virus definitions

[anatoly-os]

Do we really want it in 3.5.1, or even 3.6? I would merge this to master only (MU 4).

[Jojo-Schmitz]

Fine by me, but as long as dependencies.7z doesn't get updated, this PR doesn't make any difference

[Jojo-Schmitz]

And here the dependencies.7z for libsndfile 1.0.30 as taken from https://github.com/erikd/libsndfile/releases/tag/v1.0.30

Adding Opus support would probably not be wanted in 3.5.1, as it'd introduce new strings (for the export file selectors), even if that'd only be "Opus Audio" or "Ogg Opus Audio", which might not need to get translated at all.
But it also doesn't seem to be trivial to to add Opus support... seems that needs opusfile DLLs, but I can't find those in a ready to use build form, just the sources.

Still there is some value to be able to stay in sync with the latest libsndfile.

[Jojo-Schmitz]

It is in master now, waiting for it to get merged into 3.x for 3.6. Or a decision not to merge this into 3.x and rather close this PR

[vpereverzev]

@Jojo-Schmitz I'm not sure what this might affect for 3.x users, but one thing I know for sure, support for Opus should be in master, because it does not look like something trivial.

So since this is already merged in master, I'd close this PR for 3.x

[Jojo-Schmitz]

Without the updated dependencies this PR does nothing, but allow for an updated libsndfile
and opus support needs more than that