When texure shading is enabled, the transparency accum shaders were not set/updated.
This resulted into a crash when transparent objects were rendered when shading mode
was set to texture.
This patch will add the V3D_SHADING_TEXTURE_COLOR to the modes for OIT so the
shaders are set.
@Clément Foucault (fclem) just a sanity check that this is valid. V3D_SHADING_MATERIAL_COLOR is a fallback for when no textures are available that can result enabling the OIT; Basically OIT is enabled for most cases. Only single and random does not.