Libraries: Create top level directory for libraries.

Things were getting a little crowded in the project root, so this patch
moves the Lib*/ directories into Libraries/.

Libraries/LibCore/CLock.h

@@ -0,0 +1,125 @@
+#pragma once
+
+#ifdef __serenity__
+
+#include <AK/Assertions.h>
+#include <AK/Types.h>
+#include <unistd.h>
+
+#define memory_barrier() asm volatile("" :: \
+                                          : "memory")
+
+static inline u32 CAS(volatile u32* mem, u32 newval, u32 oldval)
+{
+    u32 ret;
+    asm volatile(
+        "cmpxchgl %2, %1"
+        : "=a"(ret), "+m"(*mem)
+        : "r"(newval), "0"(oldval)
+        : "cc", "memory");
+    return ret;
+}
+
+class CLock {
+public:
+    CLock() {}
+    ~CLock() {}
+
+    void lock();
+    void unlock();
+
+private:
+    volatile u32 m_lock { 0 };
+    u32 m_level { 0 };
+    int m_holder { -1 };
+};
+
+class CLocker {
+public:
+    [[gnu::always_inline]] inline explicit CLocker(CLock& l)
+        : m_lock(l)
+    {
+        lock();
+    }
+    [[gnu::always_inline]] inline ~CLocker() { unlock(); }
+    [[gnu::always_inline]] inline void unlock() { m_lock.unlock(); }
+    [[gnu::always_inline]] inline void lock() { m_lock.lock(); }
+
+private:
+    CLock& m_lock;
+};
+
+[[gnu::always_inline]] inline void CLock::lock()
+{
+    int tid = gettid();
+    for (;;) {
+        if (CAS(&m_lock, 1, 0) == 0) {
+            if (m_holder == -1 || m_holder == tid) {
+                m_holder = tid;
+                ++m_level;
+                memory_barrier();
+                m_lock = 0;
+                return;
+            }
+            m_lock = 0;
+        }
+        donate(m_holder);
+    }
+}
+
+inline void CLock::unlock()
+{
+    for (;;) {
+        if (CAS(&m_lock, 1, 0) == 0) {
+            ASSERT(m_holder == gettid());
+            ASSERT(m_level);
+            --m_level;
+            if (m_level) {
+                memory_barrier();
+                m_lock = 0;
+                return;
+            }
+            m_holder = -1;
+            memory_barrier();
+            m_lock = 0;
+            return;
+        }
+        donate(m_holder);
+    }
+}
+
+#define LOCKER(lock) CLocker locker(lock)
+
+template<typename T>
+class CLockable {
+public:
+    CLockable() {}
+    CLockable(T&& resource)
+        : m_resource(move(resource))
+    {
+    }
+    CLock& lock() { return m_lock; }
+    T& resource() { return m_resource; }
+
+    T lock_and_copy()
+    {
+        LOCKER(m_lock);
+        return m_resource;
+    }
+
+private:
+    T m_resource;
+    CLock m_lock;
+};
+
+#else
+
+class CLock {
+public:
+    CLock() { }
+    ~CLock() { }
+};
+
+#define LOCKER(x)
+
+#endif