Add generic intrusive FIFO queue

We need several FIFO queues (a queue of packets, a queue of messages,
etc.).

Some of them are implemented using cbuf, a generic circular buffer. But
for recording, we need to store the packets in an unbounded queue until
they are written, so the queue was implemented manually.

Create a generic implementation (using macros) to avoid reimplementing
it every time.

app/meson.build

@@ -150,6 +150,9 @@ tests = [
         'tests/test_device_msg_deserialize.c',
         'src/device_msg.c'
     ]],
+    ['test_queue', [
+        'tests/test_queue.c',
+    ]],
     ['test_strutil', [
         'tests/test_strutil.c',
         'src/str_util.c'