build: allow to disable language support in cmake

* in addition: add unloadable sourcegroup to visualize, load and save information when loading a project that contains source groups that are not supported by the build

src/lib_gui/qt/project_wizard/content/paths/QtProjectWizardContentPathsIndexedHeaders.cpp

@@ -1,5 +1,7 @@
 #include "QtProjectWizardContentPathsIndexedHeaders.h"
 
+#if BUILD_CXX_LANGUAGE_PACKAGE
+
 #include <QMessageBox>
 
 #include "CodeblocksProject.h"
@@ -251,3 +253,5 @@ void QtProjectWizardContentPathsIndexedHeaders::savedFilesDialog()
 	m_list->setPaths(dynamic_cast<QtSelectPathsDialog*>(m_filesDialog.get())->getPathsList());
 	closedFilesDialog();
 }
+
+#endif // BUILD_CXX_LANGUAGE_PACKAGE