Signed-off-by: Piotr Sikora <piotr@cloudflare.com>

This change allows to build nginx against git checkout of OpenSSL.

Signed-off-by: Piotr Sikora <piotr@cloudflare.com>

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.

Several false positive warnings silenced, notably W8012 "Comparing
signed and unsigned" (due to u_short values promoted to int), and
W8072 "Suspicious pointer arithmetic" (due to large type values added
to pointers).

With this patch, it's now again possible to compile nginx using bcc32,
with options we normally compile on win32 minus ipv6 and ssl.

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.

As of PCRE 8.33, config.h.generic no longer contains boolean macros.  Two
of them (SUPPORT_PCRE8 and HAVE_MEMMOVE) were added to appropriate makefiles.
This allows PCRE 8.33 to compile and don't change anything for previous
versions.

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

Previously, if configured with --with-cc="clang -g", the autotest.dSYM
directories were left unremoved.

The $NGX_AUTO_CONFIG_H added to perl module Makefile dependencies to
make sure it's always rebuild after a configure.  It is needed as we
expand various variables used for Makefile generation during configure
(in particular, nginx version).

Dependancy tracking introduced in r5169 were not handled absolute path
names properly.  Absolute names might appear in CORE_DEPS if --with-openssl
or --with-pcre configure arguments are used to build OpenSSL/PCRE
libraries.

Additionally, revert part of r5169 to set NGX_INCS from Makefile
variables.  Makefile variables have $ngx_include_opt in them, which
might result in wrong include paths being used.  As a side effect,
this also restores build with --with-http_perl_module and --without-http
at the same time.