wined3d: Only set GL_SHADER_OPERATION_NV to GL_NONE for supported units.

dlls/wined3d/state.c

@@ -1707,7 +1707,7 @@ static void tex_colorop(DWORD state, IWineD3DStateBlockImpl *stateblock, WineD3D
                 glDisable(GL_TEXTURE_CUBE_MAP_ARB);
                 checkGLcall("glDisable(GL_TEXTURE_CUBE_MAP_ARB)");
             }
-            if(GL_SUPPORT(NV_TEXTURE_SHADER2)) {
+            if(GL_SUPPORT(NV_TEXTURE_SHADER2) && mapped_stage < GL_LIMITS(textures)) {
                 glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_NONE);
             }
         }