Changeset 2b1b52f in mod_gnutls for include

Actually use the computed socache key in socache_delete_session()

We rely on the socache expiration rather than GnuTLS deleting cache
entries, so this function was likely never called, but if it was it
would have failed because it used the raw session ID provided by
GnuTLS rather than the derived key mod_gnutls uses for store and
fetch.