Avoid type conflict on Unix with DEC C.
Pointed out by Sergio Rabellino <Rabellino@di.unito.it>
diff --git a/apps/s_client.c b/apps/s_client.c
index 1fa1575..81617af 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -60,7 +60,7 @@
recursive header file inclusion, resulting in the compiler complaining
that u_int isn't defined, but only if _POSIX_C_SOURCE is defined, which
is needed to have fileno() declared correctly... So let's define u_int */
-#if defined(__DECC) && !defined(__U_INT)
+#if defined(VMS) && defined(__DECC) && !defined(__U_INT)
#define __U_INT
typedef unsigned int u_int;
#endif
