Get rid of the member ClassOrNamespace::_instantiations.

src/libs/cplusplus/LookupContext.cpp

@@ -615,7 +615,6 @@ ClassOrNamespace *ClassOrNamespace::nestedType(const Name *name) const
         ClassOrNamespace *i = _factory->allocClassOrNamespace(c);
         i->_templateId = templId;
         i->_usings.append(c);
-        c->_instantiations.append(i);
         return i;
     }
 

src/libs/cplusplus/LookupContext.h

@@ -107,9 +107,6 @@ private:
     // it's an instantiation.
     const TemplateNameId *_templateId;
 
-    // templates
-    QList<ClassOrNamespace *> _instantiations;
-
     friend class CreateBindings;
 };