i965/vec4: Import surface message builder functions.

i965/vec4: Import surface message builder functions.

Implement helper functions that can be used to construct and send
untyped and typed surface read, write and atomic messages to the
shared dataport unit.

v2: Split from the FS implementation.
v3: Rewrite to avoid evil array_reg, emit_collect and emit_zip.

Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>