patch 8.2.3976: FEARG_LAST is never used

Problem:    FEARG_LAST is never used. (Dominique Pellé)
Solution:   Remove FEARG_LAST and the related code.
diff --git a/src/version.c b/src/version.c
index 3b2e7d5..44af312 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3976,
+/**/
     3975,
 /**/
     3974,