fix (Qt) issues found by clang's clazy tool:

+ -Wclazy-incorrect-emit
+ -Wclazy-strict-iterators
+ -Wclazy-overloaded-signal
+ -Wclazy-qstring-arg
+ -Wclazy-unused-non-trivial-variable
+ -Wclazy-container-anti-pattern
+ -Wclazy-range-loop-reference
+ -Wclazy-const-signal-or-slot
+ -Wclazy-detaching-temporary
+ -Wclazy-qfileinfo-exists

src/Gui/Thumbnail.cpp

@@ -115,7 +115,7 @@ void Thumbnail::SaveDocFile (Base::Writer &writer) const
 
     if (!px.isNull()) {
         // according to specification add some meta-information to the image
-        uint mt = QDateTime::currentDateTime().toTime_t();
+        uint mt = QDateTime::currentDateTimeUtc().toTime_t();
         QString mtime = QString::fromLatin1("%1").arg(mt);
         img.setText(QLatin1String("Software"), qApp->applicationName());
         img.setText(QLatin1String("Thumb::Mimetype"), QLatin1String("application/x-extension-fcstd"));