message: Fix RemoveBuilders
  Summary: Fix equality of FieldsRegs. The equality on register state alone is incorrect and does not propagate the `iput`s correctly, leading to missing register moves for field stores.
diff: @@ -946,7 +946,8 @@ void FieldsRegs::meet(const FieldsRegs& that) {
  }
  bool FieldsRegs::operator==(const FieldsRegs& that) const {
  - return field_to_reg == that.field_to_reg;
  + return field_to_reg == that.field_to_reg &&
  + field_to_iput_insns == that.field_to_iput_insns;
  }
  bool FieldsRegs::operator!=(const FieldsRegs& that) const {
  