patch 8.1.2104: the normal.c file is too big

Problem:    The normal.c file is too big.
Solution:   Move do_pending_operator() to ops.c. (Yegappan Lakshmanan,
            closes #4999).

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2104,
 /**/
     2103,
 /**/