Allow CURLOPT_FOLLOWLOCATION to be used with open_basedir.

Newer versions of libcurl prevent file:// location response headers by default,
which means that the open_basedir check is unnecessary — the fact
CURLOPT_REDIR_PROTOCOLS can't set CURLPROTO_FILE with open_basedir enabled
means that there's no possibility of breaching the open_basedir restriction,
and this allows HTTP redirects to be followed automatically.

Implements FR #65646 (re-enable CURLOPT_FOLLOWLOCATION with open_basedir or
safe_mode).