AchievementManager: Return by reference from GetLock()

This makes the API a little nicer to use, since you don't need to do
a mandatory dereference when passing the lock into any kind of scope
guard.

Source/Core/DolphinQt/Achievements/AchievementHeaderWidget.cpp

@@ -62,7 +62,7 @@ AchievementHeaderWidget::AchievementHeaderWidget(QWidget* parent) : QWidget(pare
   m_total->setAlignment(Qt::AlignTop);
   setLayout(m_total);
 
-  std::lock_guard lg{*AchievementManager::GetInstance().GetLock()};
+  std::lock_guard lg{AchievementManager::GetInstance().GetLock()};
   UpdateData();
 }
 

Source/Core/DolphinQt/Achievements/AchievementLeaderboardWidget.cpp

@@ -25,7 +25,7 @@ AchievementLeaderboardWidget::AchievementLeaderboardWidget(QWidget* parent) : QW
   m_common_layout = new QGridLayout();
 
   {
-    std::lock_guard lg{*AchievementManager::GetInstance().GetLock()};
+    std::lock_guard lg{AchievementManager::GetInstance().GetLock()};
     UpdateData();
   }
 

Source/Core/DolphinQt/Achievements/AchievementProgressWidget.cpp

@@ -29,7 +29,7 @@ AchievementProgressWidget::AchievementProgressWidget(QWidget* parent) : QWidget(
   m_common_layout = new QVBoxLayout();
 
   {
-    std::lock_guard lg{*AchievementManager::GetInstance().GetLock()};
+    std::lock_guard lg{AchievementManager::GetInstance().GetLock()};
     UpdateData();
   }
 

Source/Core/DolphinQt/Achievements/AchievementsWindow.cpp

@@ -75,7 +75,7 @@ void AchievementsWindow::UpdateData()
 {
   {
     auto& instance = AchievementManager::GetInstance();
-    std::lock_guard lg{*instance.GetLock()};
+    std::lock_guard lg{instance.GetLock()};
     const bool is_game_loaded = instance.IsGameLoaded();
 
     m_header_widget->UpdateData();