cleanup: Prefer the CMake CONFIG module for CURL. (#2720)
cleanup: Prefer the CMake CONFIG module for CURL. (#2720)

This gives us the standard targets, with the correct dependencies and
flags. Fallback on the native CMake module if nothing else is available.
This is a port of the `vcpkg` patch for google-cloud-cpp, once merged we
can cleanup the patch from the `vcpkg` port.
googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp,googleapis/google-cloud-cpp