prototype wait3 and wait4

include/sys/resource.h

@@ -4,7 +4,6 @@
 #define __NEED_id_t
 #define __NEED_time_t
 #define __NEED_struct_timeval
-#define __NEED_struct_rusage
 
 #include <bits/alltypes.h>
 

include/sys/wait.h

@@ -16,8 +16,12 @@ typedef int idtype_t;
 pid_t wait (int *);
 int waitid (idtype_t, id_t, siginfo_t *, int);
 pid_t waitpid (pid_t, int *, int );
-//pid_t wait3 (int *, int, struct rusage *);
+
-//pid_t wait4 (pid_t, int *, int, struct rusage *);
+#ifdef _GNU_SOURCE
+#include <sys/resource.h>
+pid_t wait3 (int *, int, struct rusage *);
+pid_t wait4 (pid_t, int *, int, struct rusage *);
+#endif
 
 #include <bits/wait.h>
 #include <bits/wexitstatus.h>