Won't install on Windows because of dependency on the unix package for /Platform/DevLog.hs

[Andrew-Clow]

Platform/DevLog.hs uses a few System.Posix functions to test and the permissions on the hard-coded logfile path "/tmp/nri-prelude-logs" before using it.

System.Directory can supply OS-relevant locations for logfiles, so that could work around the hard coded path.

writeSpanToDevLog ensures that everyone can read and write to the logs (System.Posix.stdFileMode) before appending to it. This could perhaps be in a conditional compilation section, but I honestly don't know whether it's possible to use conditional compilation around the inclusion of the unix package in package.yaml.

If this dependency could be moved aside for those of us blighted by developing on Windows, that would be very helpful. Apologies if this is an unwelcome issue to raise.