Note that it does not work better than previous in-tree version but it will give us a better base to fix it. joint work with jasper@ most patches adapted from NetBSD fsusage patch from naddy@ ok jasper@
from Moritz Grimm <mlist at scapa.dnsalias.net> ok espie@
based on work by Alexander Wirt <alexander.wirt@credativ.de> ok ajacoutot@