Revert "Fix bug in schedule_accept()"

This reverts commit 8d59795426d88363684ca02822b063e8200c54ad.

This is a purely cosmetic change to make way for upstream commit
https://github.com/jech/polipo/commit/ee7b82d0befaea3bfcc5b5fee2cd518b41b6c04c
Don't poll for POLLOUT events in schedule_accept.

Hello, I found what I'd call an oversight in one of the startup routines. It
registers the listening filedescriptor to get both POLLOUT|POLLIN events,
the former does not really make sense here. This seems to be ignored by the
glibc/linux but when I try to run it inside cwrap's socket_wrapper I get
infinite loop where polipo tries to accept() on the socket and gets told
there isn't anything connecting.

(cherry picked from commit ee7b82d0befaea3bfcc5b5fee2cd518b41b6c04c)