updated for version 7.3.668
Problem:    Building with Perl loaded dynamically  still uses static library.
Solution:   Adjust use of PL_thr_key. (Ken Takata)
diff --git a/src/version.c b/src/version.c
index 4c93e3a..61e9c0b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -720,6 +720,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    668,
+/**/
     667,
 /**/
     666,