Upgrade from 1.13.8 to 1.13.9.
Upgrade third-party modules to their recent version.
Remove needless patches.

<ChangeLog>

*) Feature: HTTP/2 server push support; the "http2_push" and

"http2_push_preload" directives.

*) Bugfix: "header already sent" alerts might appear in logs when using

cache; the bug had appeared in 1.9.13.

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

"ssl_verify_client" directive was used and no SSL certificate was
specified in a virtual server.

*) Bugfix: in the ngx_http_v2_module.

*) Bugfix: in the ngx_http_dav_module.

</ChangeLog>