BuildSystem: Move all userpace libraries under the userspace directory

As the number of libraries is increasing, root directory starts to
expand. This adds better organization for libraries

userspace/libraries/LibC/include/monetary.h

@@ -0,0 +1,23 @@
+#ifndef _MONETARY_H
+#define _MONETARY_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/monetary.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#include <bits/types/locale_t.h>
+
+#define __need_size_t
+#include <stddef.h>
+
+#define __need_ssize_t
+#include <sys/types.h>
+
+ssize_t strfmon(char* __restrict s, size_t maxsize, const char* __restrict format, ...);
+ssize_t strfmon_l(char* __restrict s, size_t maxsize, locale_t locale, const char* __restrict format, ...);
+
+__END_DECLS
+
+#endif