hst/config: hold acl struct by value

Doc comments are also reworded for clarity.

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

cmd/hakurei/print.go

@@ -129,11 +129,8 @@ func printShowInstance(
 		}
 		if len(config.ExtraPerms) > 0 {
 			t.Printf("Extra ACL\n")
-			for _, p := range config.ExtraPerms {
-				if p == nil {
-					continue
-				}
-				t.Printf(" %s\n", p.String())
+			for i := range config.ExtraPerms {
+				t.Printf(" %s\n", config.ExtraPerms[i].String())
 			}
 			t.Printf("\n")
 		}

cmd/hakurei/print_test.go

@@ -88,7 +88,7 @@ App
  Flags:          none
 
 `, false},
-		{"config nil entries", nil, &hst.Config{Container: &hst.ContainerConfig{Filesystem: make([]hst.FilesystemConfigJSON, 1)}, ExtraPerms: make([]*hst.ExtraPermConfig, 1)}, false, false, `Error: container configuration missing path to home directory!
+		{"config nil entries", nil, &hst.Config{Container: &hst.ContainerConfig{Filesystem: make([]hst.FilesystemConfigJSON, 1)}, ExtraPerms: make([]hst.ExtraPermConfig, 1)}, false, false, `Error: container configuration missing path to home directory!
 
 App
  Identity:       0
@@ -99,6 +99,7 @@ Filesystem
  <invalid>
 
 Extra ACL
+ <invalid>
 
 `, false},
 		{"config pd dbus see", nil, &hst.Config{SessionBus: &hst.BusConfig{See: []string{"org.example.test"}}}, false, false, `Error: configuration missing container state!