tools/nolibc: drop wait4() support

Not all architectures implement the wait4() syscall. It can be
implemented in terms of the waitid() syscall, but that would require
some rework of the other wait-related functions in wait.h.

As wait4() is non-standard and deprecated, remove it.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250821-nolibc-enosys-v1-7-4b63f2caaa89@weissschuh.net

Author: t-8ch

tools/include/nolibc/sys/wait.h

@@ -16,27 +16,10 @@
 
 /*
  * pid_t wait(int *status);
- * pid_t wait4(pid_t pid, int *status, int options, struct rusage *rusage);
  * pid_t waitpid(pid_t pid, int *status, int options);
  * int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options);
  */
 
-static __attribute__((unused))
-pid_t sys_wait4(pid_t pid, int *status, int options, struct rusage *rusage)
-{
-#ifdef __NR_wait4
-	return my_syscall4(__NR_wait4, pid, status, options, rusage);
-#else
-	return __nolibc_enosys(__func__, pid, status, options, rusage);
-#endif
-}
-
-static __attribute__((unused))
-pid_t wait4(pid_t pid, int *status, int options, struct rusage *rusage)
-{
-	return __sysret(sys_wait4(pid, status, options, rusage));
-}
-
 static __attribute__((unused))
 int sys_waitid(int which, pid_t pid, siginfo_t *infop, int options, struct rusage *rusage)
 {