Always prefer constexpr when possible

app/render/rendermanager.cpp

@@ -35,9 +35,7 @@
 #include "window/mainwindow/mainwindow.h"
 
 namespace olive {
-
 RenderManager* RenderManager::instance_ = nullptr;
-const int RenderManager::kDecoderMaximumInactivity = 10000;
 
 RenderManager::RenderManager(QObject *parent) :
   ThreadPool(0, parent), backend_(kOpenGL)

app/render/rendermanager.h

@@ -144,7 +144,7 @@ private:
 
   QTimer decoder_clear_timer_;
 
-  static const int kDecoderMaximumInactivity;
+  static constexpr auto kDecoderMaximumInactivity = 10000;
 
 private slots:
   void ClearOldDecoders();