internal: remove sys package

This package is replaced by container/stub. Remove and replace it with unexported implementation for the upcoming test suite rewrite.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/hakurei/main.go

@@ -15,7 +15,6 @@ import (
 	"hakurei.app/container"
 	"hakurei.app/internal"
 	"hakurei.app/internal/hlog"
-	"hakurei.app/internal/sys"
 )
 
 var (
@@ -27,8 +26,6 @@ var (
 
 func init() { hlog.Prepare("hakurei") }
 
-var std sys.State = new(sys.Std)
-
 func main() {
 	// early init path, skips root check and duplicate PR_SET_DUMPABLE
 	container.TryArgv0(hlog.Output{}, hlog.Prepare, internal.InstallOutput)