syscall: add waitpid()

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

include/syscall-codes.h

@@ -22,6 +22,7 @@
 #define __NR_getpid		39
 #define __NR_clone		56
 #define __NR_exit		60
+#define __NR_wait4		61
 #define __NR_flock		73
 #define __NR_unlink		87
 #define __NR_tgkill		131

include/syscall.h

@@ -194,6 +194,11 @@ static always_inline long sys_read(unsigned long fd, void *buf, unsigned long co
 	return syscall3(__NR_read, fd, (unsigned long)buf, count);
 }
 
+static always_inline long sys_waitpid(int pid, int *status, int options)
+{
+	return syscall4(__NR_wait4, pid, (unsigned long)status, options, 0);
+}
+
 static always_inline long sys_exit(unsigned long error_code)
 {
 	return syscall1(__NR_exit, error_code);