Fix CppunitTest_xmlsecurity_signing with system-xmlsec 1.2.26

Swap the order of the default and custom callback registration, since
the order of lookup is now reversed since
<https://github.com/lsh123/xmlsec/commit/968646fb9b8428174a112fce2f08b1ec89d0ed97>.

Thanks Tomas Chvatal for reporting this.

(cherry picked from commit 576f8998)

xmlsecurity: check for the libxmlsec version runtime, not build-time

For the general benefit of --with-system-xmlsec usage scenarios (where
LO may be built against an old version of xmlsec and run against a new
one).

(cherry picked from commit bc4e43dd)

Change-Id: I60a347454701a679db4ccd8924a723a236d5edff
Reviewed-on: https://gerrit.libreoffice.org/55462Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
(cherry picked from commit 3d532502)
Reviewed-on: https://gerrit.libreoffice.org/55944
Tested-by: Jenkins

xmlsecurity/source/xmlsec/xmlstreamio.cxx

@@ -157,21 +157,44 @@ XSECXMLSEC_DLLPUBLIC int xmlEnableStreamInputCallbacks()
         //Notes: all none default callbacks will lose.
         xmlSecIOCleanupCallbacks() ;
 
-        //Register my classbacks.
-        int cbs = xmlSecIORegisterCallbacks(
-                    xmlStreamMatch,
-                    xmlStreamOpen,
-                    xmlStreamRead,
-                    xmlStreamClose ) ;
-        if( cbs < 0 ) {
-            return -1 ;
+        // Newer xmlsec wants the callback order in the opposite direction.
+        if (xmlSecCheckVersionExt(1, 2, 26, xmlSecCheckVersionABICompatible))
+        {
+            //Register the default callbacks.
+            //Notes: the error will cause xmlsec working problems.
+            int cbs = xmlSecIORegisterDefaultCallbacks() ;
+            if( cbs < 0 ) {
+                return -1 ;
+            }
+
+            //Register my classbacks.
+            cbs = xmlSecIORegisterCallbacks(
+                        xmlStreamMatch,
+                        xmlStreamOpen,
+                        xmlStreamRead,
+                        xmlStreamClose ) ;
+            if( cbs < 0 ) {
+                return -1 ;
+            }
         }
-
-        //Register the default callbacks.
-        //Notes: the error will cause xmlsec working problems.
-        cbs = xmlSecIORegisterDefaultCallbacks() ;
-        if( cbs < 0 ) {
-            return -1 ;
+        else
+        {
+            //Register my classbacks.
+            int cbs = xmlSecIORegisterCallbacks(
+                        xmlStreamMatch,
+                        xmlStreamOpen,
+                        xmlStreamRead,
+                        xmlStreamClose ) ;
+            if( cbs < 0 ) {
+                return -1 ;
+            }
+
+            //Register the default callbacks.
+            //Notes: the error will cause xmlsec working problems.
+            cbs = xmlSecIORegisterDefaultCallbacks() ;
+            if( cbs < 0 ) {
+                return -1 ;
+            }
         }
 
         enableXmlStreamIO |= XMLSTREAMIO_INITIALIZED ;