Now that we don't ship any modules by default, znc might be started
without any modules. Unfortunately znc refuses to start without any
modules, so patch out the appropriate check.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>

The advanced playback module makes it possible for IRC clients to avoid
undesired repetitive buffer playback. IRC clients may request the module
to send a partial buffer playback starting from and ending to a certain
point of time.

Particularly useful with (supporting) mobile clients such as Mutter,
Colloquy & others.

Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>

---

Unfortunately playback.cpp is not included as part of the standard ZNC
modules and so has been added as a patch.