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/wait.h

@@ -0,0 +1,45 @@
+#ifndef _SYS_WAIT_H
+#define _SYS_WAIT_H 1
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_wait.h.html
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_id_t
+#define __need_pid_t
+#include <sys/types.h>
+
+#include <signal.h>
+
+#define WCONTINUED	0x01
+#define WNOHANG		0x02
+#define WUNTRACED	0x04
+#define WEXITED		0x08
+#define WNOWAIT		0x10
+#define WSTOPPED	0x20
+
+#define WEXITSTATUS(status) (((status) >> 8) & 0xFF)
+#define WSTOPSIG(status) WEXITSTATUS(status)
+#define WTERMSIG(status) ((status) & 0x7F)
+#define WIFEXITED(status) (WTERMSIG(status) == 0)
+#define WIFSIGNALED(status) (((status) & 0x7F) > 0 && ((status) & 0x7F) < 0x7F)
+#define	WIFSTOPPED(status) (((status) & 0xFF) == 0x7F)
+
+#define __WGENEXITCODE(ret, sig) (((ret) << 8) | (sig))
+
+typedef enum
+{
+	P_ALL,
+	P_PGID,
+	P_PID,
+} idtype_t;
+
+pid_t	wait(int* stat_loc);
+int		waitid(idtype_t idtype, id_t id, siginfo_t* infop, int options);
+pid_t	waitpid(pid_t pid, int* stat_loc, int options);
+
+__END_DECLS
+
+#endif