context: kubernetes/kubernetes#68478
The inotify code was removed from golang.org/x/exp several years ago. Therefore
importing it from that path prevents downstream consumers from using any module
that makes use of more recent features of golang.org/x/exp.
Given that this code is by definition frozen and that the long term path should
be to migrate to fsnotify, replacing the current code by an identical standalone
copy doesn't have maintenance cost, and will unlock other activities for
kubernetes for example.
IN_ATTRIB inotify events are generated when atime / mtime is changed,
which would cause the tail to be reset, and reread the same log
again (generating duplicate events). Instead, watch the directory for
file delete / move.
Also, use an exponential backoff when retrying opening the file.
