updated for version 7.3.840

Problem:    "\@<!" in regexp does not work correctly with multi-byte
            characters, especially cp932.
Solution:   Move column to start of multi-byte character. (Yasuhiro Matsumoto)

src/version.c

@@ -728,6 +728,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    840,
 /**/
     839,
 /**/