This pulls out the cache item writing code from cache_put() into
a new helper. In this patch we also move various functions called
by this code into the new disk_cache_os.c file.
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6197>
This will make windows support easier to add in future. To avoid code
churn this temporarily duplicates the mkdir_if_needed() function, we
will delete the duplicate in a following patch.
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6197>