Re: Minor src/xmenu.c change for older GCC versions

[Richard Stallman]

    > +  FRAME_PTR f;
    > +
    >    BLOCK_INPUT;
    > -  FRAME_PTR f = check_x_frame (frame);
    > -
    > +  f = check_x_frame (frame);

Please add a comment explaining why this is necessary, to make sure
people don't take this out for elegance's sake.