Case insensitive drive comparision: Symbian SDK vs. project sources.

If SDK and Project were on te same drive but for some reason the drive
in the pathes had different cases, we had false alarms.

Made the comparision case insensitive as agreed with Tobias.

Reviewed-by: Tobias Hunger

src/plugins/qt4projectmanager/qmakestep.cpp

@@ -200,7 +200,7 @@ void QMakeStep::run(QFutureInterface<bool> &fi)
         QFileInfo cppheader(epocRootDir + QLatin1String("/epoc32/include/stdapis/string.h"));
 #if defined (Q_OS_WIN)
         // Report an error if project- and epoc directory are on different drives:
-        if (!epocRootDir.startsWith(projectDir.left(3))) {
+        if (!epocRootDir.startsWith(projectDir.left(3), Qt::CaseInsensitive)) {
             addTask(Task(Task::Error,
                          tr("The Symbian SDK and the project sources must reside on the same drive."),
                          QString(), -1, ProjectExplorer::Constants::TASK_CATEGORY_BUILDSYSTEM));