patch 8.2.0868: trim() always trims both ends

Problem:    trim() always trims both ends.
Solution:   Add an argument to only trim the beginning or end. (Yegappan
            Lakshmanan, closes #6126)

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    868,
 /**/
     867,
 /**/