i965: Add blorp-based texture upload and download paths

i965: Add blorp-based texture upload and download paths

v1 (Topi Pohjolainen): original patch.

v2 (Topi Pohjolainen):
   - Fix return value (s/MESA_FORMAT_NONE/false/) (Anuj)
   - Move _mesa_tex_format_from_format_and_type() just
     in the end avoiding additional if-block (Anuj)
   - Explain better the array alignment restriction (Anuj)
   - Do not bail out in case of gl_pixelstore_attrib::ImageHeight,
     it is handled by _mesa_image_offset() automatically (Ken).
   - Support 1D_ARRAY by flipping depth, width and y, z (Ken).

v3 (Topi Pohjolainen):
   - Contrary to v2, do not try to handle
     gl_pixelstore_attrib::ImageHeight. Currently there are no
     tests in piglit or cts for it. One could possibly copy or
     modify tests/texturing/texsubimage.c. There, however, seems
     to be number of corner cases to consider. Moreover, current
     meta path applies the packing height for both source and
     targets when determining the offset. This would probably
     require re-visiting also.

v4 (Topi Pohjolainen): Rebased on top of merged drm-bacon

v5 (Jason Ekstrand):
   - Move to brw_blorp.c
   - Significant refactoring
   - Fixed 1-D array textures
   - Simplified handling of PBOs vs. CPU data.
   - Handle gl_pixelstore_attrib::ImageHeight.  It turns out there are
     piglit tests that cover this. The original version was failing them
     because of an error in the way it handled 1-D array textures.
   - Add support for texture download

v6 (Kenneth Graunke): Rebase fixes:
   - Use intel_miptree_check_level_layer instead of deleted fields
   - Update for mesa_format_supports_render[] rename.
   - Pass 'false' (read-only) to intel_bufferobj_buffer

v7 (Kenneth Graunke):
   - Fix brw_blorp_download_miptree to pass 'false' (not read only) for
     the destination buffer (caught by Chris Wilson).
   - Fix blorp_get_client_bo to pass intel_bufferobj_buffer !read_only
     for the 'writable' parameter instead of 'false' (caught by Jason).
   - Support GL_BGR, GL_BGRA, GL_BGRA_INTEGER, GL_BGR_INTEGER, allowing
     us to use this for ReadPixels on the window system buffer (caught
     by Chris Wilson).
   - Fix y-flipping bugs in download path (exposed by BGRA support).
   - Fix false vs. NULL return value in blorp_get_client_bo.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>