patch 8.1.0992: a :normal command resets the reg_executing() result

Problem:    A :normal command while executing a register resets the
            reg_executing() result.
Solution:   Save and restore reg_executing. (closes #4066)
diff --git a/src/version.c b/src/version.c
index 1824903..4ac981e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    992,
+/**/
     991,
 /**/
     990,