BUILD: compat: fix -Wundef on SO_REUSEADDR
If USE_NETFILTER is set and not SO_REUSEPORT, we evaluate SO_REUSEADDR,
let's fix that to check that it's defined.
diff --git a/include/haproxy/compat.h b/include/haproxy/compat.h
index 19a5317..18eadcc 100644
--- a/include/haproxy/compat.h
+++ b/include/haproxy/compat.h
@@ -207,9 +207,9 @@
* USE_NETFILTER define.
*/
#if !defined(SO_REUSEPORT) && defined(USE_NETFILTER)
-#if (SO_REUSEADDR == 2)
+#if defined(SO_REUSEADDR) && (SO_REUSEADDR == 2)
#define SO_REUSEPORT 15
-#elif (SO_REUSEADDR == 0x0004)
+#elif defined(SO_REUSEADDR) && (SO_REUSEADDR == 0x0004)
#define SO_REUSEPORT 0x0200
#endif /* SO_REUSEADDR */
#endif /* SO_REUSEPORT */