dnotify as a dir watch backend is broken since Jan 2010 (almost 3.5
years). According to fd.o: #33001, it's no harm to remove dnotify from
this project.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=33001Signed-off-by: Chengwei Yang <chengwei.yang@intel.com>
Reviewed-by: Simon McVittie <simon.mcvittie@collabora.co.uk>