[WINED3D 3] Only link and use GLSL programs if at least one GLSL shader is available.

[Ivan Gyurdiev]

Ivan Gyurdiev wrote:
> I remember I ran into problems without this check... which is 
> possible, because the code will try to link and use a program even if 
> both shaders are not suitable to attach. For example there could be a 
> software vertex shader, and pixel shaders could be disabled. This 
> seems like a bad thing - skip GLSL program building of no GLSL shader 
> is available and enabled.
> ------------------------------------------------------------------------

There's something wrong with this patch... I'm not sure what it is yet, 
but it breaks certain demos in GLSL
Skip that one for now...