saml: Fix detection of datastore in SAML2 AssertionConsumerService.
saml: Fix detection of datastore in SAML2 AssertionConsumerService.

newmen/saml2,madmatt/saml2,ArtemTeleshev/php-saml2,sitya/saml2,sgomez/saml2,simplesamlphp/saml2,cb8/saml2