i965: Move brw_create_nir to brw_program.c

i965: Move brw_create_nir to brw_program.c

This way it's no longer part of libi965_compiler.la since it depends on
GLSL and ARB program stuff.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>