AK: Add Eternal<T> and use it in various places.

This is useful for static locals that never need to be destroyed:

Thing& Thing::the()
{
    static Eternal<Thing> the;
    return the;
}

The object will be allocated in data segment memory and will never have
its destructor invoked.

Kernel/StdLib.cpp

@@ -145,4 +145,14 @@ int memcmp(const void* v1, const void* v2, size_t n)
     ASSERT_NOT_REACHED();
 }
 
+void __cxa_guard_acquire(void*)
+{
+    // FIXME: Lock somehow?
+}
+
+void __cxa_guard_release(void*)
+{
+    // FIXME: Unlock somehow?
+}
+
 }