EnvWithCurrentGOOS returns a copy of os.Environ with the GOOS and GOARCH set to runtime.GOOS and runtime.GOARCH.

EnvWithGOOS retuns the os.Environ() values with GOOS and/or GOARCH either set to their runtime value, or the given value if non-empty.

SplitEnv takes the results from os.Environ() (a []string of foo=bar values) and makes a map[string]string out of it.