Replace iterator based loop by range-for-loop

Found by clazy and fixes "clazy-strict-iterators" warning.

Change-Id: I8f50c92ac054d627499440d593faa43ed5b4ad4b
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/websockets/qwebsockethandshakerequest.cpp

@@ -318,17 +318,17 @@ void QWebSocketHandshakeRequest::readHandshake(QTextStream &textStream, int maxH
     //optional headers
     m_origin = m_headers.value(QStringLiteral("origin"), QString());
     const QStringList protocolLines = m_headers.values(QStringLiteral("sec-websocket-protocol"));
-    for (QStringList::const_iterator pl = protocolLines.begin(); pl != protocolLines.end(); ++pl) {
-        QStringList protocols = (*pl).split(QStringLiteral(","), QString::SkipEmptyParts);
-        for (QStringList::const_iterator p = protocols.begin(); p != protocols.end(); ++p)
-            m_protocols << (*p).trimmed();
+    for (const QString& pl : protocolLines) {
+        const QStringList protocols = pl.split(QStringLiteral(","), QString::SkipEmptyParts);
+        for (const QString& p : protocols)
+            m_protocols << p.trimmed();
     }
+
     const QStringList extensionLines = m_headers.values(QStringLiteral("sec-websocket-extensions"));
-    for (QStringList::const_iterator el = extensionLines.begin();
-         el != extensionLines.end(); ++el) {
-        QStringList extensions = (*el).split(QStringLiteral(","), QString::SkipEmptyParts);
-        for (QStringList::const_iterator e = extensions.begin(); e != extensions.end(); ++e)
-            m_extensions << (*e).trimmed();
+    for (const QString& el : extensionLines) {
+        const QStringList extensions = el.split(QStringLiteral(","), QString::SkipEmptyParts);
+        for (const QString& e : extensions)
+            m_extensions << e.trimmed();
     }
 
     //TODO: authentication field