Won't build due to changes to how fuse-zip and rar2fs are built (workaround)

[lukebrowell]

Won't build due to changes to how fuse-zip and rar2fs are built

Temporary Workaround:

1. Disable the bits of the build that don't work in build_external.py (see commented out)

2. Download the current release, extract fuse-zip and rar2fs and copy into the executables folder after you build

Longer-term the external executables build script needs fixing so it's not as brittle. The C++ package manager I checked (Conan) doesn't currently list fuse-zip or rar2fs unfortunately - not sure what else to suggest.

[ivoronin]

Pull requests are welcome!