wined3d: Add one more FBO error status code

[Henri Verbeet]

2008/10/18 Vitaliy Margolen <wine-devel at kievinfo.com>:
> Meaning? You don't like the place where I put it into wined3d_gl.h? I can
> change that to numerical order:
>
You should add support for GL_EXT_framebuffer_multisample if you want
to use that constant. It shouldn't be much work, the extension only
introduces 3 new constants and a function.