i965/blorp: Add support for non-render-target formats.

i965/blorp: Add support for non-render-target formats.

Once blorp gains the ability to do format conversions, it's conceivable
that the source format may be texturable but not supported as a render
target.  This would break Paul's code, which assumes that it can use the
render_target_format array even for the source format.

There are three ways to convert MESA_FORMAT enums to BRW_SURFACEFORMAT
enums:

1. brw_format_for_mesa_format()

   This translates the Mesa format to the most equivalent BRW format.

2. brw->render_target_format[]

   This is used for renderbuffers, and handles the subset of formats
   that are renderable.  However, it's not always equivalent, since
   it overrides a few non-renderable formats.  For example, it
   converts B8G8R8X8_UNORM to B8G8R8A8_UNORM so it can be rendered to.

3. translate_tex_format()

   This is used for textures.  It wraps brw_format_for_mesa_format(),
   but overrides depth textures, and one sRGB case on Gen4.

BLORP has a fourth function, which uses brw->render_target_format[]
and overrides depth formats (differently than translate_tex_format).

This patch makes the BLORP function to use brw_format_for_mesa_format()
for textures/source data, since not everything will be a render target.
It continues using brw->render_target_format[] for render targets, since
it needs the format overrides that provides.

We don't use translate_tex_format() since the additional overrides are
not useful or simply redundant.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>