Go 1.13.5 for Plan 9 (arm)

After installing this package, /$cputype/go/bin should be added to
/lib/namespace.local to add GOROOT to the default namespace.

By default, the go command will install binaries to $home/go/bin,
which may not be desirable for sites with multiple cputypes.  To avoid
this issue, user profiles should be amended to either set
GOBIN=$home/bin/$cputype or bind -c $home/bin/$cputype $home/go/bin.