tools/nolibc: add support for waitid()

waitid() is the modern variant of the family of wait-like syscalls.
Some architectures have dropped support for wait(), wait4() and waitpid()
but all of them support waitid().
It is more flexible and easier to use than the older ones.

Link: https://lore.kernel.org/r/20241221-nolibc-rv32-v1-1-d9ef6dab7c63@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

tools/include/nolibc/sys.h

@@ -23,6 +23,7 @@
 #include <linux/prctl.h>
 #include <linux/resource.h>
 #include <linux/utsname.h>
+#include <linux/signal.h>
 
 #include "arch.h"
 #include "errno.h"
@@ -1225,6 +1226,23 @@ 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))
+int sys_waitid(int which, pid_t pid, siginfo_t *infop, int options, struct rusage *rusage)
+{
+	return my_syscall5(__NR_waitid, which, pid, infop, options, rusage);
+}
+
+static __attribute__((unused))
+int waitid(int which, pid_t pid, siginfo_t *infop, int options)
+{
+	return __sysret(sys_waitid(which, pid, infop, options, NULL));
+}
+
+
 /*
  * ssize_t write(int fd, const void *buf, size_t count);
  */