View format overrides -- store the mesa_format in the intel_texobj.

[chrisforbes]

We stash mesa_format in a bunch of places:

• In each teximage
• In the mt attached to each teximage
• In the mt attached to the texobj

We require, before rendering:

• All of the teximages point at the same mt
• The texobj points at the same mt as its teximages

Proposal:

• For non-views, as part of texture validation, copy the first teximage's mt->format to the intel_texobj->format. Bail out of texture validation for views before this point.
• For views, as part of view creation, apply the same transforms (separate stencil & ETC2 are the big ones) as the normal path, and store the mesa_format in intel_texobj->format.
• For renderbuffers (wrappers), copy the format from the intel_texobj rather than the mt.
• Be careful in blorp, blit copies [if we try to support pre-Gen6 views], tex upload fast path copies, ...

Meta shouldn't need anything special -- it only cares about the GL side.

[chrisforbes]

Done and works!