Qt5 fix Qt5Instance::IsMainThread()

... and I was wondering why Qt5 didn't start anymore. Looks like
it was already broken in my initial commit :-(
Now there is also no more need for the KDE5SalInstance "variant".

Change-Id: I035d31eaf191b3f2a4255869cea25394470d0dd0
Reviewed-on: https://gerrit.libreoffice.org/69577
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

vcl/qt5/Qt5Instance.cxx

@@ -378,7 +378,7 @@ void Qt5Instance::AddToRecentDocumentList(const OUString&, const OUString&, cons
 
 OpenGLContext* Qt5Instance::CreateOpenGLContext() { return new Qt5OpenGLContext; }
 
-bool Qt5Instance::IsMainThread() const { return qApp->thread() != QThread::currentThread(); }
+bool Qt5Instance::IsMainThread() const { return qApp->thread() == QThread::currentThread(); }
 
 void Qt5Instance::TriggerUserEventProcessing()
 {

vcl/unx/kde5/KDE5SalInstance.cxx

@@ -86,8 +86,6 @@ KDE5SalInstance::createFolderPicker(const uno::Reference<uno::XComponentContext>
     return uno::Reference<ui::dialogs::XFolderPicker2>(new KDE5FilePicker(QFileDialog::Directory));
 }
 
-bool KDE5SalInstance::IsMainThread() const { return qApp->thread() == QThread::currentThread(); }
-
 extern "C" {
 VCLPLUG_KDE5_PUBLIC SalInstance* create_SalInstance()
 {

vcl/unx/kde5/KDE5SalInstance.hxx

@@ -40,8 +40,6 @@ public:
     virtual css::uno::Reference<css::ui::dialogs::XFolderPicker2>
     createFolderPicker(const css::uno::Reference<css::uno::XComponentContext>&) override;
 
-    virtual bool IsMainThread() const override;
-
 private:
     virtual SalFrame* CreateFrame(SalFrame* pParent, SalFrameStyleFlags nStyle) override;