Add VZONEROOT flag because not all zone roots have VROOT set.

@@ -413,10 +413,17 @@
  * expectations about normal VFS behavior.
  */
 #define VTRAVERSE       0x80000
 
 /*
+ * Indicates the vnode is a zone's root ("/" in-zone). A zone's root does NOT
+ * have to be a filesystem root, even if many zone brands guaranteed that.
+ */
+#define VZONEROOT       0x100000
+
+
+/*
  * Vnode attributes.  A bit-mask is supplied as part of the
  * structure to indicate the attributes the caller wants to
  * set (setattr) or extract (getattr).
  */