jimtcl: update to version 0.81 (2021-11-28)

Change-Id: I374348047331b88e35b6584a5c65d8a73240b8a1
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6757
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/jimtcl b/jimtcl
index 70b007b63669a709b0e8aef34a22658047815cc2..a77ef1a6218fad4c928ddbdc03c1aedc41007e70 160000 (submodule)
--- a/jimtcl
+++ b/jimtcl
@@ -1 +1 @@
-Subproject commit 70b007b63669a709b0e8aef34a22658047815cc2
+Subproject commit a77ef1a6218fad4c928ddbdc03c1aedc41007e70