setsid() and set controlling terminal for real /sbin/init

enables job control in the test images

switch_root.c

@@ -184,6 +184,12 @@ int main(int argc, char *argv[])
 	}
 	if (access(initargs[0], X_OK))
 	  fprintf(stderr, "WARNING: can't access %s\n", initargs[0]);
+
+	/* get session leader */
+	setsid();
+	/* set controlling terminal */
+	ioctl (0, TIOCSCTTY, 1);
+
 	execv(initargs[0], initargs);
 }