tail: -F now always processes initially untailable files

tail: -F now always processes initially untailable files

which was not the case when inotify was not available.

* src/tail.c (any_live_files): Simplify, since the IGNORE
flag is now only set when a file should be ignored indefinitely.
(recheck): Only output the "giving up on name" message
when that's actually the case.  Only set the IGNORE flag
when ignoring a file indefinitely.
(tail_file): Likewise.
* tests/tail-2/retry.sh: Add a test case.  Also run
all existing test cases with and without inotify.
NEWS: Mention the fix.
THANKS.in: Add the reporter.
Fixes http://bugs.gnu.org/24495 which was detected
using Symbolic Execution techniques developed in
the course of the SYMBIOSYS research project at
COMSYS, RWTH Aachen University.