Fix deprecation warning in QGenericUnixServices

Do not use the deprecated method QProcess::start(QString) anymore.

Change-Id: I09eae2c8a1dbb53fd2de004e5030da9bb3c07b14
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/platformsupport/services/genericunix/qgenericunixservices.cpp

@@ -166,7 +166,8 @@ static inline bool launch(const QString &launcher, const QUrl &url)
 #if !QT_CONFIG(process)
     const bool ok = ::system(qPrintable(command + QLatin1String(" &")));
 #else
-    const bool ok = QProcess::startDetached(command);
+    QStringList args = QProcess::splitCommand(command);
+    const bool ok = !args.isEmpty() && QProcess::startDetached(args.takeFirst(), args);
 #endif
     if (!ok)
         qWarning("Launch failed (%s)", qPrintable(command));