Allow ssl_verify_client and ssl_verify_depth within locations

[Sebastian Wyder]

Allow the directives ssl_verify_client and ssl_verify_depth within location blocks, so that different approaches can be used when working with SSL client certificates.

It also would be useful to be able to use ssl_client_certificate and ssl_trusted_certificate within location blocks.

[Greg Smethells]

Without this feature, WebSockets are significantly less secure because it forces the client-server design to not use client verification within the TLS protocol when Secure WebSocket traffic is run over the same port as the HTTPS traffic. Browsers, including iOS Safari 6 and 7, will fail to open a WebSocket if ssl_verify_client is even set to "optional" much less "on".

[Maxim Dounin]

There are no plans to add this. Simple solution is to keep servers which require client certificates separate from ones which don't.