i965/vec4_nir: Do boolean source modifier resolves on BDW+

i965/vec4_nir: Do boolean source modifier resolves on BDW+

On BDW+, the negation source modifier on NOT, AND, OR, and XOR, is actually
a boolean negate and not an integer negate.  However, NIR's soruce
modifiers are the integer version.  We have to resolve it with a MOV prior
to emitting the actual instruction.  This is basically the same thing we do
in the FS backend.

Reviewed-by: Matt Turner <mattst88@gmail.com>