Upgrade from 1.9.5 to 1.9.6.

<ChangeLog>

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

using HTTP/2.
Thanks to Piotr Sikora and Denis Andzakovic.

*) Bugfix: the $server_protocol variable was empty when using HTTP/2.

*) Bugfix: backend SSL connections in the stream module might be timed

out unexpectedly.

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

different ssl_session_cache settings were used in different virtual
servers.

*) Bugfix: nginx/Windows could not be built with MinGW gcc; the bug had

appeared in 1.9.4.
Thanks to Kouhei Sutou.

*) Bugfix: time was not updated when the timer_resolution directive was

used on Windows.

*) Miscellaneous minor fixes and improvements.

Thanks to Markus Linnala, Kurtis Nusbaum and Piotr Sikora.

</ChangeLog>