Merge branch 'lsfds-netlink' of https://github.com/masatake/util-linux

* 'lsfds-netlink' of https://github.com/masatake/util-linux:
  tests: (lsfd) add cases for NETLINK sockets
  lsfd: use extra information loaded from /proc/net/netlink
  tests: (mkfds) add netlink factory
  tests: (lsfd,mkfds) define new error code for EPROTONOSUPPORT
  tests: (mkfds) add unsigned int parameter type
  tests: (lsfd) use ${PIPESTATUS[]} instead of $?