Fix ssl module, Python 2.7 doesn't have Py_MAX (#5878)

Signed-off-by: Christian Heimes <christian@python.org>
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index af66a58..f9ed94d 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -610,7 +610,8 @@
         }
 #elif defined(HAVE_INET_PTON)
 #ifdef ENABLE_IPV6
-        char packed[Py_MAX(sizeof(struct in_addr), sizeof(struct in6_addr))];
+	#define PySSL_MAX(x, y) (((x) > (y)) ? (x) : (y))
+        char packed[PySSL_MAX(sizeof(struct in_addr), sizeof(struct in6_addr))];
 #else
         char packed[sizeof(struct in_addr)];
 #endif /* ENABLE_IPV6 */