Several warnings silenced, notably (ngx_socket_t) -1 is now checked
on socket operations instead of -1, as ngx_socket_t is unsigned on win32
and gcc complains on comparison.

With this patch, it's now possible to compile nginx using mingw gcc,
with options we normally compile on win32.

Previously, an attempt to build pcre.lib on win32 before anything else
failed due to no pcre.h.

configuration phase.

instead of single old 4.4 version

instead, do chdir inside Makefile

options as --with-zlib=../zlib-1.2.3.  It seems there is no common way
to learn the current directory in Win32 make's: although nmake has MAKEDIR
variable, nevertheless Borland make's MAKEDIR is the directory where make
is installed, and OpenWatcom wmake has no MAKEDIR at all.

    *) Change: if the request header has duplicate the "Host",
       "Connection", "Content-Length", or "Authorization" lines, then nginx
       now returns the 400 error.

    *) Change: the "post_accept_timeout" directive was canceled.

    *) Feature: the "default", "af=", "bl=", "deferred", and "bind"
       parameters of the "listen" directive.

    *) Feature: the FreeBSD accept filters support.

    *) Feature: the Linux TCP_DEFER_ACCEPT support.

    *) Bugfix: the ngx_http_autoindex_module did not support the file names
       in UTF-8.

    *) Bugfix: the new log file can be rotated by the -USR1 signal only if
       the reconfiguration by the -HUP signal was made twice.

    *) Change: the invalid client header lines are now ignored and logged
       at the info level.

    *) Change: the server name is also logged in error log.

    *) Feature: the ngx_http_auth_basic_module module and the auth_basic
       and auth_basic_user_file directives.