TST: Add betabinom to shape-only distns in test_rvs_broadcast
TST: Add betabinom to shape-only distns in test_rvs_broadcast

`betabinom._rvs` calls `beta._rvs` and `binom._rvs`. Since it
gets more than one random number, it has to be added to the list
of distributions for shape-only testing.

e-q/scipy,nmayorov/scipy,ilayn/scipy,vigna/scipy,grlee77/scipy,tylerjereddy/scipy,andyfaff/scipy,Stefan-Endres/scipy,ilayn/scipy,rgommers/scipy,matthew-brett/scipy,endolith/scipy,andyfaff/scipy,e-q/scipy,ilayn/scipy,andyfaff/scipy,vigna/scipy,nmayorov/scipy,WarrenWeckesser/scipy,arokem/scipy,nmayorov/scipy,matthew-brett/scipy,matthew-brett/scipy,scipy/scipy,scipy/scipy,aeklant/scipy,WarrenWeckesser/scipy,mdhaber/scipy,zerothi/scipy,Eric89GXL/scipy,rgommers/scipy,person142/scipy,Stefan-Endres/scipy,rgommers/scipy,jamestwebber/scipy,anntzer/scipy,e-q/scipy,grlee77/scipy,tylerjereddy/scipy,perimosocordiae/scipy,zerothi/scipy,jamestwebber/scipy,e-q/scipy,matthew-brett/scipy,arokem/scipy,perimosocordiae/scipy,endolith/scipy,mdhaber/scipy,tylerjereddy/scipy,endolith/scipy,perimosocordiae/scipy,scipy/scipy,zerothi/scipy,pizzathief/scipy,anntzer/scipy,scipy/scipy,arokem/scipy,aeklant/scipy,endolith/scipy,Eric89GXL/scipy,tylerjereddy/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,Eric89GXL/scipy,anntzer/scipy,anntzer/scipy,perimosocordiae/scipy,Stefan-Endres/scipy,vigna/scipy,Eric89GXL/scipy,ilayn/scipy,andyfaff/scipy,endolith/scipy,scipy/scipy,pizzathief/scipy,aeklant/scipy,WarrenWeckesser/scipy,zerothi/scipy,pizzathief/scipy,ilayn/scipy,anntzer/scipy,aeklant/scipy,nmayorov/scipy,endolith/scipy,WarrenWeckesser/scipy,person142/scipy,mdhaber/scipy,matthew-brett/scipy,jamestwebber/scipy,mdhaber/scipy,pizzathief/scipy,scipy/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,rgommers/scipy,vigna/scipy,pizzathief/scipy,grlee77/scipy,tylerjereddy/scipy,grlee77/scipy,grlee77/scipy,zerothi/scipy,perimosocordiae/scipy,mdhaber/scipy,person142/scipy,mdhaber/scipy,andyfaff/scipy,jamestwebber/scipy,rgommers/scipy,arokem/scipy,perimosocordiae/scipy,e-q/scipy,WarrenWeckesser/scipy,ilayn/scipy,nmayorov/scipy,person142/scipy,jamestwebber/scipy,arokem/scipy,zerothi/scipy,aeklant/scipy,Eric89GXL/scipy,andyfaff/scipy,person142/scipy,Eric89GXL/scipy,vigna/scipy,anntzer/scipy