bug#25481: `guile --listen' broken on guile master

[Andy Wingo <wingo@pobox.com>]

On Thu 19 Jan 2017 01:47, Christopher Allan Webber <cwebber@dustycloud.org> writes:

> (originally accidentally sent to guile-devel instead of here, sorry for
> xpost!)
>
> If you use the latest Guile, you'll find that "guile --listen" has
> broken.  If you try:
>   ./meta/guile --listen=/tmp/guile-socket
>
> then you'll find that you have a very short window in which you can do:
>   M-x geiser-connect-local <RET> guile <RET> /tmp/guile-socket <RET>
>
> but then the main repl, the one you launched in the shell, hangs.
> And if you wait too long or disconnect then reconnect, you won't be
> able to connect again.
>
> What you'll see in the guile process is this:
>
>   scheme@(guile-user)> In thread:
>   ERROR: In procedure select: Interrupted system call

select really shouldn't be throwing exceptions on EINTR; it should be
called in a loop anyway, so calling scheme can run interrupts then.
Changed select to just return when async interrupts are pending
(e.g. the post-GC hooks), which seems to fix this bug.

Andy