patch 8.1.0490: MS-Windows: doesn't handle missing glibwinpthread-1.dll

Problem:    MS-Windows: doesn't handle missing glibwinpthread-1.dll.
Solution:   Adjust Cygwin/MinGW build file. (Ken Takata, closes #2827)
diff --git a/src/version.c b/src/version.c
index 01dfc13..a34837b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    490,
+/**/
     489,
 /**/
     488,