Destination alpha works in OGL. Fixed reading XFB address from VI regs and removed a check to fix games which keep the XFB some place other than mem 1.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@1921 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Plugins/Plugin_VideoOGL/Src/Render.h

@@ -116,6 +116,7 @@ public:
     static GLuint GetZBufferTarget();
 
     static void SetColorMask();
+	static void SetBlendMode(bool forceUpdate);
 	static bool SetScissorRect();
 
     static void SetRenderMode(RenderMode mode);