i965: Shrink brw_vue_map struct.

i965: Shrink brw_vue_map struct.

This patch changes the arrays in brw_vue_map (which only ever contain
values from -1 to 58) from ints to signed chars.  This reduces the
size of the struct from 488 bytes to 136 bytes.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
v2: fix STATIC_ASSERT to use 127 instead of 128.

Reviewed-by: Eric Anholt <eric@anholt.net>