Add switch for KF5 (QT6) and Mod Cmake

if we want to test QET on QT6, KF5 must be removed from the code,
this switch is for that,

this is for testing only

sources/qetdiagrameditor.cpp

@@ -42,7 +42,10 @@
 #include "undocommand/rotateselectioncommand.h"
 #include "undocommand/rotatetextscommand.h"
 
-#include <KAutoSaveFile>
+#ifdef BUILD_WITHOUT_KF5
+#else
+#	include <KAutoSaveFile>
+#endif
 
 /**
 	@brief QETDiagramEditor::QETDiagramEditor
@@ -1847,6 +1850,8 @@ bool QETDiagramEditor::drawGrid() const
 	return m_draw_grid->isChecked();
 }
 
+#ifdef BUILD_WITHOUT_KF5
+#else
 /**
 	@brief QETDiagramEditor::openBackupFiles
 	@param backup_files
@@ -1877,7 +1882,7 @@ void QETDiagramEditor::openBackupFiles(QList<KAutoSaveFile *> backup_files)
 		DialogWaiting::dropInstance();
 	}
 }
-
+#endif
 /**
 	met a jour le menu "Fenetres"
 */