qmake: replace a Q_FOREACH loop with QList::op+=

Change-Id: Ibaa49f0d6ea5cbcb5d4d305ec9c55286eac5046e
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
(cherry picked from qtbase/dce2612a7c511e85c5a1b46d1e76b88b56be4c99)
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

src/shared/proparser/qmakeevaluator.cpp

@@ -1483,11 +1483,8 @@ void QMakeEvaluator::updateFeaturePaths()
 
     QStringList feature_roots;
 
-    foreach (const QString &f, m_option->getPathListEnv(QLatin1String("QMAKEFEATURES")))
-        feature_roots += f;
-
+    feature_roots += m_option->getPathListEnv(QLatin1String("QMAKEFEATURES"));
     feature_roots += m_qmakefeatures;
-
     feature_roots += m_option->splitPathList(
                 m_option->propertyValue(ProKey("QMAKEFEATURES")).toQString(m_mtmp));