Fix build warnings in nptl/tst-eintr1.c

This patch fixes the gcc warnings seen with gcc 9.1 -O3 on s390x:
tst-eintr1.c: In function ‘tf1’:
tst-eintr1.c:46:1: error: no return statement in function returning non-void [-Werror=return-type]
   46 | }
      | ^
tst-eintr1.c: In function ‘do_test’:
tst-eintr1.c:57:17: error: unused variable ‘th’ [-Werror=unused-variable]
   57 |       pthread_t th = xpthread_create (NULL, tf1, NULL);
      |                 ^~

ChangeLog:

	* nptl/tst-eintr1.c (tf1): Add return statement.
	(do_test): Remove unused th variable.

1 files changed, 2 insertions, 3 deletions

diff --git a/nptl/tst-eintr1.c b/nptl/tst-eintr1.c
index b60b796..11404ff 100644
--- a/nptl/tst-eintr1.c
+++ b/nptl/tst-eintr1.c
@@ -43,6 +43,7 @@ tf1 (void *arg)
       pthread_t th = xpthread_create (NULL, tf2, NULL);
       xpthread_join (th);
     }
+  return NULL;
 }
 
 
@@ -53,9 +54,7 @@ do_test (void)
 
   int i;
   for (i = 0; i < 10; ++i)
-    {
-      pthread_t th = xpthread_create (NULL, tf1, NULL);
-    }
+    xpthread_create (NULL, tf1, NULL);
 
   delayed_exit (3);
   /* This call must never return.  */