Convert page_block to use kutil::linked_list

- Created a new linked_list-based slab allocator
- Simplified memory bootstrap code by using the slab allocator and
  linked_lists

src/libraries/kutil/spinlock.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <atomic>
+
+namespace kutil {
+
+
+class spinlock
+{
+public:
+	spinlock() : m_lock(false) {}
+
+	inline void enter() { while (!m_lock.exchange(true)); }
+	inline void leave() { m_lock.store(false); }
+
+private:
+	std::atomic<bool> m_lock;
+};
+
+} // namespace kutil