MFC r218688:
Mfp4 CH=177256: Catch a set vnet upon return to user space. This usually means return paths with CURVNET_RESTORE() missing. If VNET_DEBUG is turned on we can even tell the function that did the CURVNET_SET() which is really helpful; else we print "N/A". Sponsored by: The FreeBSD Foundation Sponsored by: CK Software GmbH Reviewed by: jhb