Unicorn long-since lost most of its use, due to dynarmic gaining support
for handling most instructions. At this point any further issues
encountered should be used to make dynarmic better.
This also allows us to remove our dependency on Python.
For whatever bizarre reason, Apple only made a few of std::optional's
member functions available on newer SDK versions. Given we can't even
run yuzu on macOS, and we keep the builder around to ensure that it
always at least compiles on macOS, we can bump this up a version.
Adds a cmake custom target that will build unicorn on first compile and
uses this in the build scripts as well. Updates Appveyor and Travis
build scripts to work with the new unicorn build, and updates the paths
to all of the different artifacts.
