Upgrade from 1.9.2 to 1.9.3.

<ChangeLog>

*) Change: duplicate "http", "mail", and "stream" blocks are now

disallowed.

*) Feature: connection limiting in the stream module.

*) Feature: data rate limiting in the stream module.

*) Bugfix: the "zone" directive inside the "upstream" block did not work

on Windows.

*) Bugfix: compatibility with LibreSSL in the stream module.

Thanks to Piotr Sikora.

*) Bugfix: in the "--builddir" configure parameter.

Thanks to Piotr Sikora.

*) Bugfix: the "ssl_stapling_file" directive did not work; the bug had

appeared in 1.9.2.
Thanks to Faidon Liambotis and Brandon Black.

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

"ssl_stapling" directive was used; the bug had appeared in 1.9.2.
Thanks to Matthew Baldwin.

</ChangeLog>