fix building on MacOS

[iameli]

No description provided.

[Thulinma]

I just rebased this on latest dev, which merged a lot of this in, but not everything. I think we no longer need the JSON commit - but not sure if I'm remembering that correctly. (Eli, could you confirm?)

Documenting the rest of the state for both my own future reference and others that are following along:

I kinda want to get Meson working for the Livepeer workflow, rather than merging in the CMakeLists.txt changes - partially because these changes break other workflows that we're like to keep functional 🙃.

The shared file unlink commit needs a small tweak to not break certain edge cases (where the tmpdir is non-static and/or a file from a non-tmpdir is loaded) on non-Mac - I can handle that sometime soonish, as we definitely want that one merged. Should be no big deal, but I haven't had the time yet to actually do it and it's fairly low-prio for now.

The log-related commits, I think we only need the one line change that enables proper logging on Mac - unfortunately that doesn't compile in our current cross-compiler for Mac, so we need to update the cross compiler and/or migrate to building on real Macs (probably easier to sustain and all that) - but that means it's currently blocked behind Mist's build system migrating to Drone. 🤔

I think the MIST_NO_PRETTY_LOGGING commit was for some kind of testing, right? Do we still need that, or is all fine if we just drop that commit altogether?

Finally, the 15-30 argument commit I think will be superseded by Maarten's work on proper services support in the controller - unless somebody sees a good reason to keep it regardless..?

[stronk-dev]

Mac builds using meson seems to be working now, even on the build system: https://drone.livepeer.fish/DDVTECH/mistserver/444