http: with chunked POST forced, disable length check on read callback

http: with chunked POST forced, disable length check on read callback

- when an application forces HTTP/1.1 chunked transfer encoding
  by setting the corresponding header and instructs curl to use
  the CURLOPT_READFUNCTION, disregard any POST length information.
- this establishes backward compatibility with previous curl versions

Applications are encouraged to not force "chunked", but rather
set length information for a POST. By setting -1, curl will
auto-select chunked on HTTP/1.1 and work properly on other HTTP
versions.

Reported-by: Jeff King
Origin: upstream, https://github.com/curl/curl/commit/721941aadf4adf4f6aeb3f4c0ab489bb89610c36
Last-Update: 2024-04-02

Gbp-Pq: Name fix-regression-on-chunked-post.patch