[partition] Improve type-constness

- Don't bother copying the vector of available PVs, we need the
   contained pointers.

src/modules/partition/gui/ResizeVolumeGroupDialog.cpp

@@ -1,6 +1,7 @@
 /* === This file is part of Calamares - <https://github.com/calamares> ===
  *
  *   Copyright 2018, Caio Jordão Carvalho <caiojcarvalho@gmail.com>
+ *   Copyright 2019, Adriaan de Groot <groot@kde.org>
  *
  *   Calamares is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -29,8 +30,8 @@
 #include <QSpinBox>
 
 ResizeVolumeGroupDialog::ResizeVolumeGroupDialog( LvmDevice *device,
-                                                  QVector< const Partition* > availablePVs,
+                                                  const PartitionVector& availablePVs,
-                                                  QVector< const Partition* >& selectedPVs,
+                                                  PartitionVector& selectedPVs,
                                                   QWidget* parent )
     : VolumeGroupBaseDialog( device->name(), device->physicalVolumes(), parent )
     , m_selectedPVs( selectedPVs )

src/modules/partition/gui/ResizeVolumeGroupDialog.h

@@ -1,6 +1,7 @@
 /* === This file is part of Calamares - <https://github.com/calamares> ===
  *
  *   Copyright 2018, Caio Jordão Carvalho <caiojcarvalho@gmail.com>
+ *   Copyright 2019, Adriaan de Groot <groot@kde.org>
  *
  *   Calamares is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -26,15 +27,17 @@ class LvmDevice;
 class ResizeVolumeGroupDialog : public VolumeGroupBaseDialog
 {
 public:
+    using PartitionVector = QVector< const Partition* >;
+
     ResizeVolumeGroupDialog( LvmDevice *device,
-                             QVector< const Partition* > availablePVs,
+                             const PartitionVector& availablePVs,
-                             QVector< const Partition* >& selectedPVs,
+                             PartitionVector& selectedPVs,
                              QWidget* parent );
 
     void accept() override;
 
 private:
-    QVector< const Partition* >& m_selectedPVs;
+    PartitionVector& m_selectedPVs;
 };
 
 #endif // RESIZEVOLUMEGROUPDIALOG_H