i965: Move fs_inst::has_side_effects()'s eot check to the parent class.

This eliminates a layer of wrapping, and makes a backend_instruction
sufficient.  The downside is that it exposes 'eot' to the vec4 backend,
which it doesn't need, but can basically happily ignore.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Tested-by: Pallavi G <pallavi.g@intel.com>

src/intel/compiler/brw_vec4_visitor.cpp

@@ -46,6 +46,7 @@ vec4_instruction::vec4_instruction(enum opcode opcode, const dst_reg &dst,
    this->predicate_inverse = false;
    this->target = 0;
    this->shadow_compare = false;
+   this->eot = false;
    this->ir = NULL;
    this->urb_write_flags = BRW_URB_WRITE_NO_FLAGS;
    this->header_size = 0;