Support unserializing broker data into type 'any'

The receiver side will wrap the data as a Broker::Data value, which
can then be type-checked/cast via 'is' or 'as' operators to a specific
Bro type.  For example:

Sender:

    Broker::publish("topic", my_event, "hello")

Receiver:

    event my_event(arg: any)
        {
        if ( arg is string )
            print arg as string;
        }

src/broker/Data.cc

@@ -772,6 +772,9 @@ struct type_checker {
 
 Val* bro_broker::data_to_val(broker::data d, BroType* type)
 	{
+	if ( type->Tag() == TYPE_ANY )
+		return bro_broker::make_data_val(move(d));
+
 	return broker::visit(val_converter{type}, std::move(d));
 	}
 

testing/btest/Baseline/broker.remote_event_any/recv.recv.out

@@ -0,0 +1,12 @@
+receiver added peer: endpoint=127.0.0.1 msg=handshake successful
+is_remote should be T, and is, T
+receiver got ping: my-message, 1
+is_remote should be T, and is, T
+receiver got ping: my-message, 2
+is_remote should be T, and is, T
+receiver got ping: my-message, 3
+is_remote should be T, and is, T
+receiver got ping: my-message, 4
+is_remote should be T, and is, T
+receiver got ping: my-message, 5
+[num_peers=1, num_stores=0, num_pending_queries=0, num_events_incoming=5, num_events_outgoing=4, num_logs_incoming=0, num_logs_outgoing=1, num_ids_incoming=0, num_ids_outgoing=0]

testing/btest/Baseline/broker.remote_event_any/send.send.out

@@ -0,0 +1,11 @@
+is_remote should be F, and is, F
+sender added peer: endpoint=127.0.0.1 msg=received handshake from remote core
+is_remote should be T, and is, T
+sender got pong: my-message, 1
+is_remote should be T, and is, T
+sender got pong: my-message, 2
+is_remote should be T, and is, T
+sender got pong: my-message, 3
+is_remote should be T, and is, T
+sender got pong: my-message, 4
+sender lost peer: endpoint=127.0.0.1 msg=lost remote peer

testing/btest/broker/remote_event_any.bro

@@ -0,0 +1,107 @@
+# @TEST-SERIALIZE: comm
+#
+# @TEST-EXEC: btest-bg-run recv "bro -B broker -b ../recv.bro >recv.out"
+# @TEST-EXEC: btest-bg-run send "bro -B broker -b ../send.bro >send.out"
+#
+# @TEST-EXEC: btest-bg-wait 20
+# @TEST-EXEC: btest-diff recv/recv.out
+# @TEST-EXEC: btest-diff send/send.out
+
+@TEST-START-FILE send.bro
+
+redef Broker::default_connect_retry=1secs;
+redef Broker::default_listen_retry=1secs;
+redef exit_only_after_terminate = T;
+
+global event_count = 0;
+
+global ping: event(msg: string, c: any);
+
+event bro_init()
+    {
+    Broker::subscribe("bro/event/my_topic");
+    Broker::peer("127.0.0.1");
+    print "is_remote should be F, and is", is_remote_event();
+    }
+
+function send_event()
+    {
+    ++event_count;
+    local e = Broker::make_event(ping, "my-message", event_count);
+    Broker::publish("bro/event/my_topic", e);
+    }
+
+event Broker::peer_added(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print fmt("sender added peer: endpoint=%s msg=%s",
+    endpoint$network$address, msg);
+    send_event();
+    }
+
+event Broker::peer_lost(endpoint: Broker::EndpointInfo, msg: string)
+    {
+    print fmt("sender lost peer: endpoint=%s msg=%s",
+    endpoint$network$address, msg);
+    terminate();
+    }
+
+event pong(msg: string, n: any)
+    {
+    print "is_remote should be T, and is", is_remote_event();
+
+    if ( n is count )
+        print fmt("sender got pong: %s, %s", msg, n as count);
+
+    send_event();
+    }
+
+@TEST-END-FILE
+
+
+@TEST-START-FILE recv.bro
+
+redef Broker::default_connect_retry=1secs;
+redef Broker::default_listen_retry=1secs;
+redef exit_only_after_terminate = T;
+
+const events_to_recv = 5;
+
+global handler: event(msg: string, c: count);
+global auto_handler: event(msg: string, c: count);
+
+global pong: event(msg: string, c: count);
+
+event bro_init()
+        {
+        Broker::subscribe("bro/event/my_topic");
+        Broker::listen("127.0.0.1");
+        }
+
+event Broker::peer_added(endpoint: Broker::EndpointInfo, msg: string)
+        {
+        print fmt("receiver added peer: endpoint=%s msg=%s", endpoint$network$address, msg);
+        }
+
+event Broker::peer_lost(endpoint: Broker::EndpointInfo, msg: string)
+        {
+        print fmt("receiver lost peer: endpoint=%s msg=%s", endpoint$network$address, msg);
+        }
+
+event ping(msg: string, n: any)
+        {
+        print "is_remote should be T, and is", is_remote_event();
+
+        if ( n is count )
+        	print fmt("receiver got ping: %s, %s", msg, n as count);
+
+        if ( (n as count) == events_to_recv )
+                {
+		print get_broker_stats();
+                terminate();
+                return;
+                }
+
+        Broker::publish("bro/event/my_topic", pong, msg, n as count);
+        }
+
+@TEST-END-FILE