OpenRCT2: update to 0.3.2

[klardotsh]

Update to 0.3.1, the new title sequences directory, the scripting API, and all the other funsies that came in the new version.

I playtested this for a few minutes online on x86_64-musl and I see nothing obviously broken yet.

[ericonr]

Cross builds seem to be building fine, I tested armv6l-musl. Didn't test at runtime.

[klardotsh]

Since 0.3.2 came out today, I went ahead and bumped this PR to target the new version instead. This required a change to json-c++ to build the multi-header version rather than the single-header version. Based on the multi-header version's json.hpp, this should be a backwards-compatible change.

Game still builds and runs on x86_64-musl.

[klardotsh]

I'm not entirely sure what's up with the CI failures. I had that locally, and had to manually build the update to json-c++, and I don't know off the top of my head what makes that version dependency inconsistently invalid...

[ericonr]

Please replace the two unzip commands with bsdtar ones, if possible, then remove unzip from hostmakedepends.

[the-maldridge]

Going to accept this with unzip for now. It would be nice to use bsdtar, but I ran into a strange bug locally when I tried this.