re-enable testing for PPC in emulation

[h-vetinari]

Spurred by the success of conda-forge/numpy-feedstock#274, let's try for scipy as well

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[h-vetinari]

I almost can't believe my eyes 🤩

(context: this issues had existed for ~years, since well before since #186, which merely surfaced it; the first occurrence I remember is this; c.f. also the much-later opened upstream issue)