patch 7.4.1779

Problem:    Using negative index in strcharpart(). (Yegappan Lakshmanan)
Solution:   Assume single byte when using a negative iindex.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1779,
 /**/
     1778,
 /**/