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).
diff --git a/src/version.c b/src/version.c
index fe9cee3..29273b5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2104,
+/**/
     2103,
 /**/
     2102,