updated for version 7.4.321
Problem:    Can't build with strawberry perl 5.20 + mingw-w64-4.9.0.
Solution:   Define save_strlen. (Ken Takata)
diff --git a/src/version.c b/src/version.c
index 0df080e..a876bf8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -735,6 +735,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    321,
+/**/
     320,
 /**/
     319,