updated build.xh
updated build.xh

PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack