On the svn-auth-x509 branch, accept newer signature algorithms like sha256.

We're not verifying the signature and our intentions with this code
will never likely have us needing to do so.  I could just extend the
accepted object id range up to 13 which would allow sha256, sha384 and
sha512, but in the long run we'd have to keep updating this code.  We could
also just keep checking for the PKCS#1 object id prefix on the signature
algorithm, but again there's no guarantee that future signature algorithms
will continue to receive object ids in this namespace.  The only reason we
would care about the signature algorithm is we start to actually check it,
in which case we'd want to know we supported the algorithm.  So I consider
removal of the checks entirely the better long term solution for our purposes.

* subversion/libsvn_subr/x509parse.c
  (svn_x509_parse_cert): Just remove the check for the signature algorithm.
    


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1605645 13f79535-47bb-0310-9956-ffa450edef68