patch 8.1.0020: cannot tell whether a register is executing or recording

Problem:    Cannot tell whether a register is being used for executing or
            recording.
Solution:   Add reg_executing() and reg_recording(). (Hirohito Higashi,
            closes #2745)  Rename the global variables for consistency.  Store
            the register name in reg_executing.
diff --git a/src/edit.c b/src/edit.c
index ef4c98d..1ae8e2d 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -8698,7 +8698,7 @@
      * When recording or for CTRL-O, need to display the new mode.
      * Otherwise remove the mode message.
      */
-    if (Recording || restart_edit != NUL)
+    if (reg_recording != 0 || restart_edit != NUL)
 	showmode();
     else if (p_smd)
 	MSG("");