Added support for `buildcache`.
Added support for `buildcache`.

Look for `clcache`/`ccache` only if we can't find `buildcache`.

cellml/libcellml,nickerso/libcellml,hsorby/libcellml,cellml/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml,nickerso/libcellml,hsorby/libcellml