i965: Add compiler options to brw_compiler

i965: Add compiler options to brw_compiler

This creates the options at screen cration time and then we just copy them
into the context at context creation time.  We also move is_scalar to the
brw_compiler structure.

We also end up manually setting some values that the core would have set by
default for us.  Fortunately, there are only two non-zero shader compiler
option defaults that we aren't overriding anyway so this isn't a big deal.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>