audio: fix WAVState leak

Spotted by ASAN.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170503223846.6559-4-marcandre.lureau@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

audio/wavcapture.c

@@ -88,6 +88,7 @@ static void wav_capture_destroy (void *opaque)
     WAVState *wav = opaque;
 
     AUD_del_capture (wav->cap, wav);
+    g_free (wav);
 }
 
 static void wav_capture_info (void *opaque)