Moved Oculus enable drawing to user side...

Still thinking about the best way to manage this...

examples/core_oculus_rift.c

@@ -52,6 +52,8 @@ int main()
         BeginDrawing();
 
             ClearBackground(RAYWHITE);
+            
+            if (IsOculusReady()) BeginOculusDrawing();
 
             Begin3dMode(camera);
 
@@ -62,6 +64,8 @@ int main()
             
             End3dMode();
             
+            if (IsOculusReady()) EndOculusDrawing();
+            
             DrawFPS(10, 10);
 
         EndDrawing();