Merge branch 'lsfd--SIOCGSKNS-based-SOCK_NETNS' of https://github.com/masatake/util...

* 'lsfd--SIOCGSKNS-based-SOCK_NETNS' of https://github.com/masatake/util-linux:
  lsfd: fill SOCK.NETNS even when sock_diag netlink can't report sockets
  tests: (test_mkfds:netns) conditionally report EPERM when ioctl(SIOCGSKNS) fails
  tests: (test_mkfd::tcp-bare) new factory creating an unbound/unconnected TCP socket
  lsfd: add inspect_target_fd method to file_class
  lsfd: (refactor) make call_with_foreign_fd reusable
  lsfd: make pidfd for the target process available while collecting fds
  lsfd: (comment) update the description of sock_xinfo::netns_inode
  lsfd: (cosmetic) delete an empty line