For three component textures virgl faces the problem that the host driver
may report that these can not be used as a render target, and when the
client requests such a texture a four-componet texture will be choosen
even if only a sampler view was requested. One example where this happens
is with the Intel i965 driver that doesn't support RGB32* as render target.
The result is that when allocating a GL_RGB32F and a GL_RGB32I texture, and
then glCopyImageSubData is called for these two texture, gallium will fail
with an assertion, because it reports a different per pixel bit count.

Therefore, when using the virgl driver, don't try to enable BIND_RENDER_TARGET
for RGB textures that were requested with only BIND_SAMPLER_VIEW.