move KEYBASE_SKIP_* env vars to build()
move KEYBASE_SKIP_* env vars to build()

They had no effect in package(), because the build was already done.
Oops.

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client