SIGINT like pressing control-c

[anki-code]

Originally posted by @jonathanslenders in xonsh/xonsh#3628 (comment):

If I recall correctly, prompt_toolkit does not set any signal handlers, because potentially it runs in a different thread (where setting signal handlers doesn't work in Python). However, it handles control-c by setting the terminal in raw mode and reading control-c literally from the input.
Would you like an external SIGINT to behave exactly like pressing control-c?
(assuming prompt_toolkit does run in the main thread.)
If so, feel free to open a issue in the prompt_toolkit issue tracker. That way I won't forget.

[jonathanslenders]

Possible fix: #1538 (Not yet tested extensively.)

[jonathanslenders]

Closing this issue. That fix was merged and released.