If video backend initialization fails, have the emulator die gracefully instead of crashing the application. Also a little clean up of the passage of the video window handle to the backend and back.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@7248 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/Common/Src/VideoBackendBase.h

@@ -86,7 +86,7 @@ public:
 
 	virtual unsigned int PeekMessages() = 0;
 
-	virtual void Initialize() = 0;
+	virtual bool Initialize(void *&) = 0;
 	virtual void Shutdown() = 0;
 
 	virtual void DoState(PointerWrap &p) = 0;