Fix and use correct pointers and types.

Should have been `XMLDeclaration* decl = ...` instead of `XMLElement* ele = ...`
diff --git a/tinyxml2.cpp b/tinyxml2.cpp
index 377ad23..2f6a5b9 100755
--- a/tinyxml2.cpp
+++ b/tinyxml2.cpp
@@ -887,7 +887,7 @@
             break;

         }

 

-        XMLElement* ele = node->ToDeclaration();

+        XMLDeclaration* decl = node->ToDeclaration();

         if ( decl ) {

                 // A declaration can only be the first child of a document.

                 // Set error, if document already has children.