tools/nolibc/sys: add syscall definition for getppid()

This is essentially for completeness as it's not the most often used
in regtests.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/sys.h

@@ -464,6 +464,23 @@ pid_t getpid(void)
 }
 
 
+/*
+ * pid_t getppid(void);
+ */
+
+static __attribute__((unused))
+pid_t sys_getppid(void)
+{
+	return my_syscall0(__NR_getppid);
+}
+
+static __attribute__((unused))
+pid_t getppid(void)
+{
+	return sys_getppid();
+}
+
+
 /*
  * pid_t gettid(void);
  */