tests: fix warnings

While I don't see -Werror being used on tests anytime soon, there's no
reason to keep the warnings in tests unfixed.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/tests/test-segv.c b/tests/test-segv.c
index 55bd25a..1b851fc 100644
--- a/tests/test-segv.c
+++ b/tests/test-segv.c
@@ -35,7 +35,7 @@
 
 struct thread_master *master;
 
-int
+static int
 threadfunc (struct thread *thread)
 {
   int *null = NULL;