[portaudio] Add iOS patches

[fwcd]

This adds PortAudio/portaudio#881 to PortAudio, enabling builds targeting iOS. Once upstreamed, these patches can be removed.

[daschuer]

All green. How is the IOS branch compiled? Can we cross-compile it like the M1 build?

[fwcd]

Pretty much, most packages should build by just targeting arm64-ios(-release)

[daschuer]

Do you plan to add a CI runner for this?

[fwcd]

Yes. There are some more missing patches for it to run through, but I'll see if I can open a PR soon.

[fwcd]

Cross-compiling Qt for arm64 iOS will likely be similar to arm64 macOS in that debug builds will likely not be feasible. How would you suggest doing this under the current branching scheme? Should we add arm64-ios-release CI to both 2.5 and 2.5-rel, or just 2.5-rel?

[daschuer]

With the package cache, incremental builds are possible. So we may need two attempts to have everything build.
But do we relay need the debug build? If not let's save some energy and only introduce the arm64-ios-release.
We can add the debug builds at any time later.

[fwcd]

Yeah, my question was more around the branching scheme (IMO release builds are perfectly sufficient), i.e. whether we should add iOS (arm64-ios-release) CI to the (non-rel) 2.5 branch too? If so, should we add CI for arm64-osx-release to 2.5 too, which currently is only tested in 2.5-rel?

[daschuer]

That's a good idea. This is now possible with the new scheme and we can uses it.