i965/msaa: Expand odd-sized MSAA surfaces to account for interleaving pattern.

i965/msaa: Expand odd-sized MSAA surfaces to account for interleaving pattern.

Gen6 MSAA buffers (and Gen7 MSAA depth/stencil buffers) interleave
MSAA samples in a complex pattern that repeats every 2x2 pixel block.
Therefore, when allocating an MSAA buffer, we need to make sure to
allocate an integer number of 2x2 blocks; if we don't, then some of
the samples in the last row and column will be cut off.

Fixes piglit tests "EXT_framebuffer_multisample/unaligned-blit {2,4}
color msaa" on i965/Gen6.

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>