xmlseclibs: Remove SAML20 and Shib13 specific appendSignature, and replace with original.
xmlseclibs: Remove SAML20 and Shib13 specific appendSignature, and replace with original.

tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp,tectronics/simplesamlphp,vivekrajenderan/simplesamlphp,vivekrajenderan/simplesamlphp,tectronics/simplesamlphp