Go 1.16 is already old, and the GOOS detection code fails for me on
Nix:
$ go run gioui.org/cmd/gogio -target ios ../gio-example/kitchen
gogio: go tool dist list failed: go tool dist: FAILED: not a Git repo; must put a VERSION file in $GOROOT
The error message points to a Nix packaging issue, but removing the
fallback is easier to fix.
Signed-off-by: Elias Naur <mail@eliasnaur.com>