Use of accept mutex on win32 may result in a deadlock if there are multiple
worker_processes configured and the mutex is grabbed by a process which
can't accept connections.

This fixes connection hang with websockets proxy, and likely some other
places as well.

The parameter is mostly identical to http_404, and is expected to
be used in similar situations.  The 403 code might be returned by
a backend instead of 404 on initial sync of new directories with rsync.

See here for feature request and additional details:
http://mailman.nginx.org/pipermail/nginx-ru/2013-April/050920.html

Directive is similar to ssi_last_modified and sub_filter_last_modified
directives introduced by previous commits.

Directive is similar to ssi_last_modified introduced by previous commit.

Patch by Alexey Kolpakov.

The "ssi_last_modified" directive allows to preserve Last-Modified header
in SSI responses.  The directive is similar to SSILastModified one available
in Apache:

http://httpd.apache.org/docs/2.4/mod/mod_include.html#ssilastmodified

Patch by Alexey Kolpakov.

It is now a syntax error if tokens passed to a custom configuration
handler are terminated by "{".

The following incorrect configuration is now properly rejected:

  map $v $v2 {
      a b {
      c d {
      e f {
  }

An invalid memcached reply that started with '\n' could cause
segmentation fault.

An invalid memcached reply "VALUE / 0 2\r?ok\r\nEND\r\n" was
considered as a valid response.

In addition, if memcached reports that the key was not found,
set u->headers_in.content_length_n to 0.  This ensures that
ngx_http_memcached_filter() will not be called while previous
code relied on always intercepting 404.  Initialization of
ctx->rest was moved to where it belongs.