Upgrade from 1.11.8 to 1.11.9.

<ChangeLog>

*) Bugfix: nginx might hog CPU when using the stream module; the bug had

appeared in 1.11.5.

*) Bugfix: EXTERNAL authentication mechanism in mail proxy was accepted

even if it was not enabled in the configuration.

*) Bugfix: a segmentation fault might occur in a worker process if the

"ssl_verify_client" directive of the stream module was used.

*) Bugfix: the "ssl_verify_client" directive of the stream module might

not work.

*) Bugfix: closing keepalive connections due to no free worker

connections might be too aggressive.
Thanks to Joel Cunningham.

*) Bugfix: an incorrect response might be returned when using the

"sendfile" directive on FreeBSD and macOS; the bug had appeared in
1.7.8.

*) Bugfix: a truncated response might be stored in cache when using the

"aio_write" directive.

*) Bugfix: a socket leak might occur when using the "aio_write"

directive.

</ChangeLog>