Merge pull request #2189 from jbj/eivc-2019

C++: Minor tweaks to ExprInVoidContext

Author: geoffw0

cpp/ql/src/semmle/code/cpp/commons/VoidContext.qll

@@ -35,7 +35,8 @@ private predicate exprInVoidContext(Expr e) {
     exists(CommaExpr c | c.getLeftOperand() = e)
     or
     exists(CommaExpr c | c.getRightOperand() = e and c instanceof ExprInVoidContext)
+    or
+    exists(ForStmt for | for.getUpdate() = e)
   ) and
-  not e instanceof Qualifier and
   not e.getActualType() instanceof VoidType
 }