build.sh: Suppress stderr of which
build.sh: Suppress stderr of which

Some implementations of which write to stderr on error.

alkadis/vcv,DanielNeugebauer/adhocracy,alkadis/vcv,alkadis/vcv,phihag/adhocracy,phihag/adhocracy,phihag/adhocracy,liqd/adhocracy,alkadis/vcv,liqd/adhocracy,phihag/adhocracy,DanielNeugebauer/adhocracy,DanielNeugebauer/adhocracy,phihag/adhocracy,DanielNeugebauer/adhocracy,liqd/adhocracy,alkadis/vcv,DanielNeugebauer/adhocracy,liqd/adhocracy