LibThread: Introduce a new threading library

This library is meant to provide C++-style wrappers over lower
level APIs such as syscalls and pthread_* functions, as well as
utilities for easily running pieces of logic on different
threads.

Libraries/LibThread/Thread.cpp

@@ -0,0 +1,39 @@
+#include <LibThread/Thread.h>
+#include <unistd.h>
+
+LibThread::Thread::Thread(Function<int()> action)
+    : CObject(nullptr)
+    , m_action(move(action))
+{
+}
+
+LibThread::Thread::~Thread()
+{
+    if (m_tid != -1) {
+        dbg() << "trying to destroy a running thread!";
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void LibThread::Thread::start()
+{
+    int rc = create_thread([](void* arg) {
+        Thread* self = static_cast<Thread*>(arg);
+        int exit_code = self->m_action();
+        self->m_tid = -1;
+        exit_thread(exit_code);
+        return exit_code;
+    }, static_cast<void*>(this));
+
+    ASSERT(rc > 0);
+    dbg() << "Started a thread, tid = " << rc;
+    m_tid = rc;
+}
+
+void LibThread::Thread::quit(int code)
+{
+    ASSERT(m_tid == gettid());
+
+    m_tid = -1;
+    exit_thread(code);
+}