Check the realm string before trying to close the stream.

This avoids a potential case where the realm string never gets compared and
so the hash still gets returned to the caller.  This is mostly a theoretical
issue since the caller is almost certainly going to do nothing with the hash
if it gets an error.

* subversion/libsvn_subr/config_auth.c
  (svn_config_read_auth_data): Move the svn_stream_close() after we've
    checked the realm string.

Found by: danielsh


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1600909 13f79535-47bb-0310-9956-ffa450edef68