It was failing about an unaccepted risk ("mac-app-connector") because
it was checking runtime.GOOS ("darwin") instead of the test's env.goos
string value ("linux", which doesn't have the warning).
Fixes#14544
Change-Id: I470d86a6ad4bb18e1dd99d334538e56556147835
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>