tail: revert to polling if a followed directory is replaced

tail: revert to polling if a followed directory is replaced

* src/tail.c (tail_forever_inotify): Add the IN_DELETE_SELF flag when
creating watch for the parent directory.  After the parent directory
is removed, an event is caught and then we switch from inotify to
polling mode.  Till now, inotify has always frozen because it waited for
an event from a watched dir, which has been already deleted and was not
added again.
* tests/tail-2/inotify-dir-recreate.sh: Add a test case.
* tests/local.mk: Reference the new test.
* NEWS: Mention the bug fix.
Fixes http://bugs.gnu.org/26363
Reported at https://bugzilla.redhat.com/1283760