bug#32640: 26.1; Make `kill-process' a command

[Phil Sainty]

(Apologies for the terseness of the previous message -- I managed
to send it accidentally when I'd barely started writing it.)

To repeat:

Not being able to use M-x kill-process (especially for killing
the current buffer's process) is something which has annoyed me
periodically.

`kill-process' is written in C, but it occurred to me to see
whether I could give it an interactive-form property, and was
pleased to find that it worked. What I've written seems to work
nicely -- a completing read over the `process-list' (filtered
by process-type `real'), and with the current buffer's process
provided by default.

I'm not proposing this (see attachment in previous message) as
a patch verbatim -- if this change was made, I would expect
`kill-process' to *directly* declare itself as interactive in
the C code -- but potentially `kill-process-read-arg' could be
used as I've written it (or similar) if that was agreeable?


-Phil