hst: optionally cover /run/ early

This works around awkward root permissions.

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

cmd/app/app.go

@@ -83,6 +83,8 @@ func parse(id string, base *check.Absolute, r io.Reader) (*hst.Config, error) {
 			Home:     home,
 			Path:     shell,
 			Args:     []string{"zsh", "-c"},
+
+			Flags: hst.FCoverRun,
 		},
 	}