Juan A. Suárez authored Mar 31, 2016 and Alejandro Piñeiro committed May 17, 2016

VS Thread Payload handles attributes in URB as vec4, no matter if they
are actually single or double precision.

So with double-precision types, value ends up in the registers split in
32bits chunks, in different positions.

We need to shuffle the chunks to get the doubles correctly.

v2:
 * Extra blank line. Add { } on if body (Ian Romanick)
 * Use dest directly (Kenneth Graunke)

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>