segfault on rl_completion_matches() interrupt

[Raphaël Droz]

Using both 4.2 and 4.3, I can reproduce a segfault on completion (though
not using gdb)

This can happen very consistently using a time-consuming completion like
the one for `man`, eg:
$ man g<tab><tab>^C


Attached is the trace from a core-file using `man gpg-agent g<tab><tab>^C`
with bash 4.3.


Side note: as more and more completions take time to finish (think ssh,
dpkg, ...), having ^G to interrupt the completion process and not having
to use ^C which discard the whole line could be useful.

bash-comp-int-crash.gdb.log
Description: Text document