intel: Refactor intel_render_texture() [v2]

intel: Refactor intel_render_texture() [v2]

This is in preparation for properly implementing glFramebufferTexture*()
for mipmapped depthstencil textures. The FIXME comments deleted by this
patch give a rough explanation of what was broken.

This refactor does the following:
   - In intel_update_wrapper() and intel_wrap_texture(), change the
     parameters to prepare to remove functions' dependency on
     gl_texture_image.
   - Move the call to intel_renderbuffer_set_draw_offsets() from
     intel_render_texture() into intel_udpate_wrapper().

Each time I encounter those functions, I dislike their vague names.
(Update which wrapper? What is wrapped? What is the wrapper?). So, while
I was mucking around, I also renamed the functions.

v2:
   In addition to the ``GLenum internal_format`` parameter to
   intel_wrap_miptree(), add a ``gl_format format`` parameter. This
   removes the need to recalculate for the true format from
   internal_format with ChooseNewTextureFormat, which was just weird.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>