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)
diff --git a/src/version.c b/src/version.c
index 4b09557..c75283f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    868,
+/**/
     867,
 /**/
     866,