[GIT-PULLS] [php-src] PR #22967: ftp: use SSL_write_ex() in single_send() to fix signed/unsigned handling

Pull Request: https://github.com/php/php-src/pull/22967
Author: crystarm

This continues #19912, adding a fix for the outstanding review comment from @ndossche that hadn't been addressed yet.

The first commit here (by @zeff-ir) replaces `SSL_write()` with `SSL_write_ex()`, which reports success/failure via its own `int` return value while writing the number of bytes sent through a separate `size_t*` out-parameter — avoiding the conversion issue entirely and matching the OpenSSL API contract.

The second commit finishes the fix requested in review: `single_send()` still narrowed its result to `int` on return (`return (int)sent;`), even though it now computes a `size_t` (from `SSL_write_ex()`) or an `ssize_t` (from `my_send_wrapper_with_restart()` in the non-SSL path). Returning `ssize_t` instead avoids a theoretical truncation/overflow for writes larger than `INT_MAX`, which could otherwise collide with the `-1` error sentinel checked by the caller (`my_send()`) or corrupt its buffer pointer arithmetic.

In case this PR is accepted, #19912 should be closed.