Merge branch 'lsfd--eventfd' of https://github.com/masatake/util-linux

* 'lsfd--eventfd' of https://github.com/masatake/util-linux:
  test_mkfds: avoid "ignoring return value of ‘write’ declared with attribute ‘warn_unused_result’"
  tests: (lsfd) add cases for eventfd
  tests: (mkfds) add eventfd factory
  tests: (mkfds) provide the way to declare the number of extra printing values
  tests: (mkfds) print a whitespace only when the running factory has "report" method
  lsfd: fill ENDPOINTS column for eventfd
  lsfd: add a helper macro, foreach_endpoint
  lsfd: add a helper function, init_endpoint
  lsfd: add a helper function, add_endpoint
  lsfd: add a helper function, new_ipc
  lsfd: add a back pointer as a member of anon_eventfd_data
  lsfd: move a local variable to a narrower scope
  lsfd: add EVENTFD.ID column
  lsfd: delete redundant parentheses surrounding return value
  ldfd: delete unnecessary ';'
  lsfd: choose anon_ops declarative way