MAINT: stats: remove an _argcheck call
MAINT: stats: remove an _argcheck call

This was needed when _argcheck could set the .a and .b attributes. Since it
no longer does, the call is not needed. The attributes are set in _get_support
which is, literally, the next line.

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