bug#68338: 30.0.50; Repeat mode and input methods

[Juri Linkov]

>> IOW define something like a `keymap-transient-p` function, use it there,
>> and make sure the keymaps installed by `set-transient-map` are recognized
>> by that new function.

I had a similar problem while implementing buffer-local isearch-mode in
https://lists.gnu.org/archive/html/emacs-devel/2021-05/msg00490.html

The proposed solution was to put a special property on the symbol:

  (put 'isearch-mode 'overriding-keymap t)

Although it has limited applicability, I couldn't find a better way.
This might be ok for the isearch keymap, but definitely not suitable
for transient keysmaps that often are not bound to a symbol.

> Maybe we can treat all `overriding-terminal-local-map` as "transient" in
> this respect, as in the patch below.
>
> It's a bit risky, admittedly.  But it would be useful to know what
> breaks when we do that, to get a better understanding about what the
> condition above should really test.

I confirm the patch fixes this bug report while keeping the test case
from bug#22958 working.  In any case this is better than hard-coding
special-handling of universal-argument-map.