jack: don't use legacy packet API

Instead, use a jack_ringbuffer which is shared between the thread
calling Play() and JACK's audio Process() thread. The ringbuffer is
a lock-free structure, safe for one writer and one reader thread to
use.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/audio_output/Modules.am

@@ -53,7 +53,7 @@ if HAVE_PULSE
 libvlc_LTLIBRARIES += libpulse_plugin.la
 endif
 
-libjack_plugin_la_SOURCES = jack.c packet.c volume.h
+libjack_plugin_la_SOURCES = jack.c volume.h
 libjack_plugin_la_CFLAGS = $(AM_CFLAGS) $(JACK_CFLAGS)
 libjack_plugin_la_LIBADD = $(AM_LIBADD) $(JACK_LIBS) $(LIBM)
 EXTRA_LTLIBRARIES += libjack_plugin.la