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/dlfcn.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define RTLD_LAZY 1
+#define RTLD_NOW 2
+#define RTLD_GLOBAL 3
+#define RTLD_LOCAL 4
+
+int dlclose(void*);
+char* dlerror();
+void* dlopen(const char*, int);
+void* dlsym(void*, const char*);
+
+__END_DECLS