This patch fixes incorrect handling of auto redirect in configurations
like:

    location /0  { }
    location /a- { }
    location /a/ { proxy_pass ... }

With previously used sorting, this resulted in the following locations
tree (as "-" is less than "/"):

        "/a-"
    "/0"    "/a/"

and a request to "/a" didn't match "/a/" with auto_redirect, as it
didn't traverse relevant tree node during lookup (it tested "/a-",
then "/0", and then falled back to null location).

To preserve locale use for non-ASCII characters on case-insensetive
systems, libc's tolower() used.

Found by using auth_basic.t from mdounin nginx-tests under valgrind.

==10470== Invalid write of size 1
==10470==    at 0x43603D: ngx_crypt_to64 (ngx_crypt.c:168)
==10470==    by 0x43648E: ngx_crypt (ngx_crypt.c:153)
==10470==    by 0x489D8B: ngx_http_auth_basic_crypt_handler (ngx_http_auth_basic_module.c:297)
==10470==    by 0x48A24A: ngx_http_auth_basic_handler (ngx_http_auth_basic_module.c:240)
==10470==    by 0x44EAB9: ngx_http_core_access_phase (ngx_http_core_module.c:1121)
==10470==    by 0x44A822: ngx_http_core_run_phases (ngx_http_core_module.c:895)
==10470==    by 0x44A932: ngx_http_handler (ngx_http_core_module.c:878)
==10470==    by 0x455EEF: ngx_http_process_request (ngx_http_request.c:1852)
==10470==    by 0x456527: ngx_http_process_request_headers (ngx_http_request.c:1283)
==10470==    by 0x456A91: ngx_http_process_request_line (ngx_http_request.c:964)
==10470==    by 0x457097: ngx_http_wait_request_handler (ngx_http_request.c:486)
==10470==    by 0x4411EE: ngx_epoll_process_events (ngx_epoll_module.c:691)
==10470==  Address 0x5866fab is 0 bytes after a block of size 27 alloc'd
==10470==    at 0x4A074CD: malloc (vg_replace_malloc.c:236)
==10470==    by 0x43B251: ngx_alloc (ngx_alloc.c:22)
==10470==    by 0x421B0D: ngx_malloc (ngx_palloc.c:119)
==10470==    by 0x421B65: ngx_pnalloc (ngx_palloc.c:147)
==10470==    by 0x436368: ngx_crypt (ngx_crypt.c:140)
==10470==    by 0x489D8B: ngx_http_auth_basic_crypt_handler (ngx_http_auth_basic_module.c:297)
==10470==    by 0x48A24A: ngx_http_auth_basic_handler (ngx_http_auth_basic_module.c:240)
==10470==    by 0x44EAB9: ngx_http_core_access_phase (ngx_http_core_module.c:1121)
==10470==    by 0x44A822: ngx_http_core_run_phases (ngx_http_core_module.c:895)
==10470==    by 0x44A932: ngx_http_handler (ngx_http_core_module.c:878)
==10470==    by 0x455EEF: ngx_http_process_request (ngx_http_request.c:1852)
==10470==    by 0x456527: ngx_http_process_request_headers (ngx_http_request.c:1283)
==10470==

The same path names with different "data" context should not be allowed.

In particular it rejects configurations like this:

    proxy_cache_path /var/cache/ keys_zone=one:10m max_size=1g inactive=5m;
    proxy_cache_path /var/cache/ keys_zone=two:20m max_size=4m inactive=30s;

An instance of ngx_path_t is already zeroed by ngx_pcalloc().

It initializes the "data" pointer of ngx_path_t that will be checked after
subsequent changes.

Casts between pointers and integers produce warnings on size mismatch.  To
silence them, cast to (u)intptr_t should be used.  Prevoiusly, casts to
ngx_(u)int_t were used in some cases, and several ngx_int_t expressions had
no casts.

As of now it's mostly style as ngx_int_t is defined as intptr_t.

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.

Precompiled headers are disabled as they lead to internal compiler errors
with long configure lines.  Couple of false positive warnings silenced.
Various win32 typedefs are adjusted to work with Open Watcom C 1.9 headers.

With this patch, it's now again possible to compile nginx using owc386,
with options we normally compile on win32 minus ipv6 and ssl.

It is surplus.