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

There was a bug report attached to the copy of 511cfd3bffa (http: add
custom hostname to IP address resolutions, 2022-05-16) in the `git/git`
repository on GitHub, claiming that that commit broke the build on
RedHat Enterprise Linux 6. The most likely explanation is that the
available cURL version does not support the `CURLOPT_RESOLVE` feature.

Let's work around this by warning the user if they configure
`http.curloptResolve` if compiled against a too-old cURL version.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Submitted-As: https://lore.kernel.org/git/pull.1277.git.1656692646303.gitgitgadget@gmail.com