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/sys/shm.h

@@ -0,0 +1,42 @@
+#ifndef _SYS_SHM_H
+#define _SYS_SHM_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_shm.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_pid_t
+#define __need_size_t
+#define __need_time_t
+#include <sys/types.h>
+
+#include <sys/ipc.h>
+
+#define SHM_RDONLY	0x01
+#define SHM_RDONLY	0x02
+#define SHM_RDONLY	0x04
+
+typedef unsigned int shmatt_t;
+
+struct shmid_ds
+{
+	struct ipc_perm	shm_perm;	/* Operation permission structure. */
+	size_t			shm_segsz;	/* Size of segment in bytes. */
+	pid_t			shm_lpid;	/* Process ID of last shared memory operation. */
+	pid_t			shm_cpid;	/* Process ID of creator. */
+	shmatt_t		shm_nattch;	/* Number of current attaches. */
+	time_t			shm_atime;	/* Time of last shmat(). */
+	time_t			shm_dtime;	/* Time of last shmdt(). */
+	time_t			shm_ctime;	/* Time of last change by shmctl().*/
+};
+
+void*	shmat(int shmid, const void* shmaddr, int shmflg);
+int		shmctl(int shmid, int cmd, struct shmid_ds* buf);
+int		shmdt(const void* shmaddr);
+int		shmget(key_t key, size_t size, int shmflg);
+
+__END_DECLS
+
+#endif