Lagom: Add a simple IPC client and server for host-side testing

Add LibIPC to the Lagom build, and also implement two little test apps
so we can run IPC tests on other systems.

Lagom/SimpleIPCClient.cpp

@@ -0,0 +1,39 @@
+#include <LibCore/CEventLoop.h>
+#include <LibCore/CTimer.h>
+#include <LibCore/CoreIPCClient.h>
+#include <stdio.h>
+#include "SimpleEndpoint.h"
+
+class SimpleIPCClient : public IPC::Client::ConnectionNG<SimpleEndpoint> {
+    C_OBJECT(SimpleIPCClient)
+public:
+    SimpleIPCClient()
+        : ConnectionNG("/tmp/simple-ipc")
+    {}
+
+    virtual void handshake() override {}
+
+    i32 compute_sum(i32 a, i32 b, i32 c)
+    {
+        return send_sync<Simple::ComputeSum>(a, b, c)->sum();
+    }
+};
+
+int main(int, char**)
+{
+    CEventLoop event_loop;
+
+    SimpleIPCClient client;
+
+    CTimer timer(100, [&] {
+        i32 sum = client.compute_sum(1, 2, 3);
+        dbg() << "Sum: " << sum;
+    });
+
+    CTimer kill_timer(5000, [&] {
+        dbg() << "Timer fired, good-bye! :^)";
+        event_loop.quit(0);
+    });
+
+    return event_loop.exec();
+}