Blind attempt to fix ODR violations
Remove apparently useless "link_with" directive. Even if this isn't the
root cause, it makes the .build file more like the other test modules.
Reviewed by Masahiko Sawada
Follow-up to
ee1b30f12, per buildfarm members olingo and grassquit.
Discussion: https://postgr.es/m/CANWCAZaJAaO8MimTU%2BY-DZutM6HQLQu%3DK2HyoQULdB3v_6BSCg%40mail.gmail.com