It was broken by X-Forwarded-For related changes in f7fe817c92a2 (1.3.14)
as hh->offset is no longer 0 for Cookie.

As of 1.3.9, chunked request body may be available with
r->headers_in.content_length_n <= 0.  Additionally, request body
may be in multiple buffers even if r->request_body_in_single_buf
was requested.

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.

To avoid further breaks it's now done properly, all the dependencies
are now passed to Makefile.PL.  While here, fixed include list passed to
Makefile.PL to use Makefile variables rather than a list expanded during
configure.

It's no longer necessary to update src/http/modules/perl/nginx.pm
when version is bumped, as it's now derived from src/core/nginx.h.