[PATCH 3/3] http-push: avoid new compile error

From: Johannes Schindelin <johannes.schindelin@gmx.de>

With the recent update in Git for Windows/ARM64 as of https://github.com/git-for-windows/git-sdk-arm64/commit/21b288e16358 cURL was updated from v8.15.0 to v8.16.0, and the LLVM-based builds (but strangely not the GCC-based builds) continuously greet me thusly:

  http-push.c:211:2: error: call to '_curl_easy_setopt_err_long' declared
  with 'warning' attribute: curl_easy_setopt expects a long argument
  [-Werror,-Wattribute-warning]
      CC builtin/apply.o
    211 |         curl_easy_setopt(curl, CURLOPT_INFILESIZE, buffer->buf.len);
        |         ^
  C:/a/git-sdk-arm64/git-sdk-arm64/minimal-sdk/clangarm64/include/curl/typecheck-gcc.h:50:15:
  note: expanded from macro 'curl_easy_setopt'
     50 |               _curl_easy_setopt_err_long();                             \
        |               ^
  1 error generated.
  make: *** [Makefile:2877: http-push.o] Error 1

The easiest way to shut up that compile error (which is legitimate, seeing as the `CURLOPT_INFILESIZE` options expects a `long` parameter, but `buffer->buf.len` refers to the `size_t` attribute of a `strbuf`) would be to simply cast the parameter to a `long`.

However, there is a much better solution: To use the `CURLOPT_INFILESIZE_LARGE` option instead, which was added in cURL v7.11.0 (see https://curl.se/ch/7.11.0.html) and which Git _already_ uses in `curl_append_msgs_to_imap()`.

This fix was the motivation for renaming `xcurl_off_t()` to `cast_size_t_to_curl_off_t()` and making it available more broadly, which is the reason why it is used here, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 http-push.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)