QSettings/QConfFile: Fix reading on NTFS symbolic links

The code checked on QFileInfo::size() whether the file had any content.
The check failed for NTFS symbolic links since QFileInfo::size() returns 0
for them. Workaround by using QFile::size() instead.

Task-number: QTBUG-64121
Change-Id: I303414b5a560d1ed8fbc53d969e53f9e2899ae5c
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qsettings.cpp

@@ -1451,7 +1451,7 @@ void QConfFileSettingsPrivate::syncConfFile(QConfFile *confFile)
             Files that we can't read (because of permissions or
             because they don't exist) are treated as empty files.
         */
-        if (file.isReadable() && fileInfo.size() != 0) {
+        if (file.isReadable() && file.size() != 0) {
             bool ok = false;
 #ifdef Q_OS_MAC
             if (format == QSettings::NativeFormat) {