patch 9.0.1485: no functions for converting from/to UTF-16 index

Problem:    no functions for converting from/to UTF-16 index.
Solution:   Add UTF-16 flag to existing funtions and add strutf16len() and
            utf16idx(). (Yegappan Lakshmanan, closes #12216)
diff --git a/src/version.c b/src/version.c
index e5099dd..0ce90eb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1485,
+/**/
     1484,
 /**/
     1483,