Add include files to prevent warnings on some (HPUX) systems.

tests/libtest/lib503.c

@@ -1,5 +1,11 @@
 #include "test.h"
 
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#include <sys/time.h>
+#include <sys/types.h>
+
 /*
  * Source code in here hugely as reported in bug report 651460 by
  * Christopher R. Palmer.

tests/libtest/lib504.c

@@ -1,5 +1,11 @@
 #include "test.h"
 
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#include <sys/time.h>
+#include <sys/types.h>
+
 /*
  * Source code in here hugely as reported in bug report 651464 by
  * Christopher R. Palmer.