C++: Add missing getUnspecifiedType in AV Rule 82

Adding this call to `getUnspecifiedType` makes the error message better
in the presence of typedefs and qualifiers on an assignment operator
return type. It's also needed to avoid losing valid results in the
commit that comes after this.

cpp/ql/src/jsf/4.10 Classes/AV Rule 82.ql

@@ -76,7 +76,7 @@ predicate assignOperatorWithWrongType(Operator op, string msg) {
   and exists(op.getBlock())
   and exists(Class c |
         c = op.getDeclaringType()
-    and op.getType() = c
+    and op.getType().getUnspecifiedType() = c
     and msg = "Assignment operator in class " + c.getName() + " should have return type " + c.getName() + "&. Otherwise a copy is created at each call."
   )
 }

cpp/ql/test/query-tests/jsf/4.10 Classes/AV Rule 82/AV Rule 82.expected

@@ -3,5 +3,5 @@
 | AV Rule 82.cpp:63:29:63:29 | operator= | Assignment operator in class TemplateReturnAssignment<int> does not return a reference to *this. |
 | AV Rule 82.cpp:63:29:63:37 | operator= | Assignment operator in class TemplateReturnAssignment<T> does not return a reference to *this. |
 | AV Rule 82.cpp:192:55:192:63 | operator= | Assignment operator in class TemplatedAssignmentGood does not return a reference to *this. |
-| AV Rule 82.cpp:199:52:199:52 | operator= | Assignment operator in class TemplatedAssignmentBad does not return a reference to *this. |
+| AV Rule 82.cpp:199:52:199:52 | operator= | Assignment operator in class TemplatedAssignmentBad should have return type TemplatedAssignmentBad&. Otherwise a copy is created at each call. |
 | AV Rule 82.cpp:199:52:199:60 | operator= | Assignment operator in class TemplatedAssignmentBad does not return a reference to *this. |