smbd: Simplify inotify_handler()

smbd: Simplify inotify_handler()

[sizeof(struct inotify_event) + NAME_MAX + 1] is the recommended
buffer size in "man 7 inotify". Pulling everything out of the inotify
buffer makes sense if we would reliably get the two rename events in
the same read-call. Unfortunately this is not the case, even with a
buffer size of 64k I've seen MOVED_FROM and MOVED_to in separate reads
from the socket. We'll have to take care of this situation next. Until
then, we don't have to FIONREAD and then read everything that's
there. Rather go through another event loop, replacing the ioctl with
a epoll_wait syscall.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=15864
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>