patch 7.4.1742

Problem:    strgetchar() does not work correctly.
Solution:   use mb_cptr2len().  Add a test. (Naruhiko Nishino)

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1742,
 /**/
     1741,
 /**/