This is probably unsafe, and doesn't protect against symlink loops,
but we will eventually add this when we bring update*.c and inotify*.c
closer together.
This shouldn't really happen, but insane users might delete/rename the
music directory while MPD runs. What was even more insane was that
MPD crashed due to this. This is a workaround - there is currently
nothing useful we can do in this case; except maybe poll for the music
directory to reappear, but that's too much trouble for a user error.
This is useful at the maximum depth level, to update newly created
directories. It is however questionable if the hard-coded 5 seconds
delay is enough to create new directory trees with all of their files,
but we might make that delay configurable in the future.
This patch implements a light-weight inotify library, and watches all
directories below the music directory. It updates all directories
where files changed after a delay of 5 seconds.
