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/grp.h

@@ -0,0 +1,31 @@
+#ifndef _GRP_H
+#define _GRP_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/grp.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_gid_t
+#define __need_size_t
+#include <sys/types.h>
+
+struct group
+{
+	char* gr_name;	/* The name of the group. */
+	gid_t gr_gid;	/* Numerical group ID. */
+	char** gr_mem;	/* Pointer to a null-terminated array of character pointers to member names. */
+};
+
+void			endgrent(void);
+struct group*	getgrent(void);
+struct group*	getgrgid(gid_t gid);
+int				getgrgit_r(gid_t gid, struct group* grp, char* buffer, size_t bufsize, struct group** result);
+struct group*	getgrnam(const char* name);
+int				getgrnam_r(const char* name, struct group* grp, char* buffer, size_t bufsize, struct group** result);
+void			setgrent(void);
+
+__END_DECLS
+
+#endif