Remove dependency on QFSFileEngine

The code was hard-wired to use QFSFileEngine to determine platform
preference for file system case sensitivity. In this case it is cheaper
to use private API and directly access the information in
QFileSystemEngine.

This change is also necessary because file engines are being dropped
from the public API.

Change-Id: I5015d5fdb3979af9ff2d114084053ad06220d834
Reviewed-by: Shane Kearns <ext-shane.2.kearns@nokia.com>

src/widgets/dialogs/qfileinfogatherer_p.h

@@ -58,13 +58,14 @@
 #include <qwaitcondition.h>
 #include <qfilesystemwatcher.h>
 #include <qfileiconprovider.h>
-#include <qfsfileengine.h>
 #include <qpair.h>
 #include <qstack.h>
 #include <qdatetime.h>
 #include <qdir.h>
 #include <qelapsedtimer.h>
 
+#include <private/qfilesystemengine_p.h>
+
 QT_BEGIN_NAMESPACE
 
 class QExtendedInformation {
@@ -86,8 +87,7 @@ public:
 
 #ifndef QT_NO_FSFILEENGINE
     bool isCaseSensitive() const {
-        QFSFileEngine fe(mFileInfo.absoluteFilePath());
-        return fe.caseSensitive();
+        return QFileSystemEngine::isCaseSensitive();
     }
 #endif