[kernel] Move bind_irq syscall to new system object

In order to implement capabilities on system resources like IRQs so that
they may be restricted to drivers only, add a new 'system' kobject type,
and move the bind_irq functionality from endpoint to system.

Also fix some stack bugs passing the initial handles to a program.

src/kernel/device_manager.cpp

@@ -67,6 +67,9 @@ device_manager::device_manager() :
 {
 	m_irqs.ensure_capacity(32);
 	m_irqs.set_size(16);
+	for (int i = 0; i < 16; ++i)
+		m_irqs[i] = nullptr;
+
 	m_irqs[2] = ignore_endpoint;
 }