CGuiWidgetDrawParms: Make constexpr constructible

We can allow this structure to be constructed in a constexpr context.

This also allows us to remove the cpp file, given it's no longer
necessary.

Runtime/MP1/CSamusHud.cpp

@@ -1429,7 +1429,7 @@ void CSamusHud::Draw(const CStateManager& mgr, float alpha, CInGameGuiManager::E
     }
 
     if (x274_loadedFrmeBaseHud) {
-      x274_loadedFrmeBaseHud->Draw(CGuiWidgetDrawParms::Default);
+      x274_loadedFrmeBaseHud->Draw(CGuiWidgetDrawParms::Default());
     }
   }