message: relocate from container

This package is quite useful. This change allows it to be imported without importing container.

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

ldd/exec.go

@@ -13,6 +13,7 @@ import (
 	"hakurei.app/container/check"
 	"hakurei.app/container/fhs"
 	"hakurei.app/container/seccomp"
+	"hakurei.app/message"
 )
 
 const (
@@ -25,7 +26,7 @@ var (
 	msgStaticGlibc = []byte("not a dynamic executable")
 )
 
-func Exec(ctx context.Context, msg container.Msg, p string) ([]*Entry, error) {
+func Exec(ctx context.Context, msg message.Msg, p string) ([]*Entry, error) {
 	c, cancel := context.WithTimeout(ctx, lddTimeout)
 	defer cancel()