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/LibC/assert.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#ifdef DEBUG
+__attribute__((noreturn)) void __assertion_failed(const char* msg, const char* file, unsigned line, const char* func);
+#    define assert(expr) ((expr) ? (void)0 : __assertion_failed(#    expr, __FILE__, __LINE__, __PRETTY_FUNCTION__))
+#    define ASSERT_NOT_REACHED() assert(false)
+#else
+#    define assert(expr)
+#    define ASSERT_NOT_REACHED() CRASH()
+#endif
+
+#define CRASH()              \
+    do {                     \
+        asm volatile("ud2"); \
+    } while (0)
+#define ASSERT assert
+#define RELEASE_ASSERT assert
+
+__END_DECLS