zeroconf/Avahi: call dbus_shutdown() during shutdown

Make valgrind happy.

configure.ac

@@ -825,7 +825,7 @@ avahi)
 	;;
 esac
 
-MPD_AUTO_PKG(avahi, AVAHI, [avahi-client],
+MPD_AUTO_PKG(avahi, AVAHI, [avahi-client dbus-1],
 	[avahi client library], [avahi-client not found])
 if test x$enable_avahi = xyes; then
 	AC_DEFINE([HAVE_AVAHI], 1, [Define to enable Avahi Zeroconf support])

src/zeroconf/ZeroconfAvahi.cxx

@@ -34,6 +34,8 @@
 #include <avahi-common/malloc.h>
 #include <avahi-common/error.h>
 
+#include <dbus/dbus.h>
+
 static constexpr Domain avahi_domain("avahi");
 
 static char *avahiName;
@@ -272,4 +274,6 @@ AvahiDeinit(void)
 
 	avahi_free(avahiName);
 	avahiName = nullptr;
+
+	dbus_shutdown();
 }

valgrind.suppressions

@@ -297,34 +297,6 @@
    fun:dlclose
 }
 
-# is that a leak in libdbus?
-
-{
-   <insert a suppression name here>
-   Memcheck:Leak
-   fun:?alloc
-   ...
-   obj:*/libdbus-*.so.*
-   fun:avahi_client_new
-}
-
-{
-   <insert a suppression name here>
-   Memcheck:Leak
-   fun:malloc
-   obj:/usr/lib/libdbus-1.so.3.4.0
-   fun:dbus_message_new_error
-   obj:/usr/lib/libdbus-1.so.3.4.0
-   fun:dbus_connection_send_with_reply
-   fun:dbus_connection_send_with_reply_and_block
-   obj:/usr/lib/libavahi-client.so.3.2.4
-   fun:avahi_entry_group_new
-   fun:avahiRegisterService
-   fun:avahiClientCallback
-   obj:/usr/lib/libavahi-client.so.3.2.4
-   fun:avahi_client_new
-}
-
 {
    inet_ntoa
    Memcheck:Leak