C++: Also suppress ExprHasNoEffect in declspec etc

Author: jbj

cpp/ql/src/Likely Bugs/Likely Typos/ExprHasNoEffect.ql

@@ -86,6 +86,7 @@ where
   not peivc.isFromTemplateInstantiation(_) and
   parent = peivc.getParent() and
   not parent.isInMacroExpansion() and
+  not peivc.isUnevaluated() and
   not parent instanceof PureExprInVoidContext and
   not peivc.getEnclosingFunction().isCompilerGenerated() and
   not peivc.getType() instanceof UnknownType and