Fix minor bug causing svnserve gssapi (and possibly other sasl backends) to deadlock, as the client never sends the response the server is looking for.
Fix minor bug causing svnserve gssapi (and possibly other sasl
backends) to deadlock, as the client never sends the response the
server is looking for.

* subversion/libsvn_ra_svn/cyrus_auth.c
  (try_auth): If sasl_client_step returns SASL_CONTINUE, we must
    send something to the server even if sasl_client_step set out
    to NULL; that just means we send the empty string, so do so.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@869315 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion