openidProvider: Fix cross-site scripting.
openidProvider: Fix cross-site scripting.

If someone is able to perform a session fixation attack on the
openidProvider host, he can then make users execute scripts in that
domain.

git-svn-id: a243b28a2a52d65555a829a95c8c333076d39ae1@2445 44740490-163a-0410-bde0-09ae8108e29a

simplesamlphp/simplesamlphp-module-openidprovider