Merge branch 'lsfs--sockdiag-RW' of https://github.com/masatake/util-linux

Merge branch 'lsfs--sockdiag-RW' of https://github.com/masatake/util-linux

* 'lsfs--sockdiag-RW' of https://github.com/masatake/util-linux:
  lsfd: (man) update the description of ENDPOINTS column of UNIX-Stream sockets
  tests: (lsfd) extend the mkfds-socketpair case to test ENDPOINTS with SOCK.SHUTDOWN info
  lsfd: append SOCK.SHUTDOWN value to ENDPOINTS column of UNIX-STREAM sockets
  tests: (lsfd) add a case for testing SOCK.SHUTDOWN column
  tests: (test_mkfds::socketpair) add "halfclose" parameter
  lsfd: don't capitalize the help strings for the columns
  lsfd: (man) write about SOCK.SHUTDOWN column
  lsfd: add SOCK.SHUTDOWN column
  lsfd: call xinfo backend method before calling socket generic method when filling columns
  tests: (lsfd) add a case for testing ENDPOINTS column of UNIX-STREAM sockets
  tests: (lsfd::mkfds-socketpair) make a case for testing DGRAM a subtest and add a subtest for STREAM
  lsfd: (man) document the ENDPOINT column for UNIX socket
  lsfd: fill ENDPOINTS column of unix socket using UNIX_DIAG_PEER information
  lsfd: make the sock_xinfo layer be able to prepare an ipc_class for a given socket
  lsfd: initialize the ipc table before loading lists of unix socket peers via netlink diag