When prototyping behavior is not explicitly specified, xsubpp emits
a message to stderr asking to do so (see ticket #608).

Resolved warnings about declarations that hide previous local declarations.
Warnings about WSASocketA() being deprecated resolved by explicit use of
WSASocketW() instead of WSASocket().  When compiling without IPv6 support,
WinSock deprecated warnings are disabled to allow use of gethostbyname().

The following configuration with alias, nested location and try_files
resulted in wrong file being used.  Request "/foo/test.gif" tried to
use "/tmp//foo/test.gif" instead of "/tmp/test.gif":

    location /foo/ {
        alias /tmp/;
        location ~ gif {
            try_files $uri =405;
        }
    }

Additionally, rev. c985d90a8d1f introduced a regression if
the "/tmp//foo/test.gif" file was found (ticket #768).  Resulting URI
was set to "gif?/foo/test.gif", as the code used clcf->name of current
location ("location ~ gif") instead of parent one ("location /foo/").

Fix is to use r->uri instead of clcf->name in all cases in the
ngx_http_core_try_files_phase() function.  It is expected to be
already matched and identical to the clcf->name of the right
location.

If alias was used in a location given by a regular expression,
nginx used to do wrong thing in try_files if a location name (i.e.,
regular expression) was an exact prefix of URI.  The following
configuration triggered a segmentation fault on a request to "/mail":

    location ~ /mail {
        alias /path/to/directory;
        try_files $uri =404;
    }

Reported by Per Hansson.

Iterating through all connections takes a lot of CPU time, especially
with large number of worker connections configured.  As a result
nginx processes used to consume CPU time during graceful shutdown.
To mitigate this we now only do a full scan for idle connections when
shutdown signal is received.

Transitions of connections to idle ones are now expected to be
avoided if the ngx_exiting flag is set.  The upstream keepalive module
was modified to follow this.