Fix uninitialized variables

src/collection/collectionbackend.cpp

@@ -55,6 +55,7 @@
 CollectionBackend::CollectionBackend(QObject *parent) :
     CollectionBackendInterface(parent),
     db_(nullptr),
+    source_(Song::Source_Unknown),
     original_thread_(nullptr) {
 
   original_thread_ = thread();

src/collection/collectionview.cpp

@@ -93,6 +93,7 @@ CollectionView::CollectionView(QWidget *parent)
       action_show_in_browser_(nullptr),
       action_show_in_various_(nullptr),
       action_no_show_in_various_(nullptr),
+      action_delete_files_(nullptr),
       is_in_keyboard_search_(false),
       delete_files_(false)
   {

src/collection/savedgroupingmanager.cpp

@@ -49,7 +49,8 @@
 SavedGroupingManager::SavedGroupingManager(QWidget *parent)
     : QDialog(parent),
       ui_(new Ui_SavedGroupingManager),
-      model_(new QStandardItemModel(0, 4, this)) {
+      model_(new QStandardItemModel(0, 4, this)),
+      filter_(nullptr) {
 
   ui_->setupUi(this);