hst/config: handle filesystem entry targeting root

This allows any fstype supported by hst to be directly mounted on sysroot. A special case in internal/app applies the matching entry early and excludes it from path hiding.

Closes #5.

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

cmd/hakurei/print.go

@@ -110,10 +110,6 @@ func printShowInstance(
 		}
 		t.Printf(" Flags:\t%s\n", strings.Join(flags, " "))
 
-		if params.AutoRoot != nil {
-			t.Printf(" Root:\t%s (%d)\n", params.AutoRoot, params.RootFlags)
-		}
-
 		etc := params.Etc
 		if etc == nil {
 			etc = container.AbsFHSEtc