Removed reference to update-core
Removed reference to update-core

It's `pacman -Su` nowadays, per https://github.com/Alexpux/MSYS2-pacman/pull/26.

(This is a very selective cherry-pick of #11392. The other parts were more controversial; they didn't fully work so let's disregard them for now.)

dsandeephegde/servo,avadacatavra/servo,paulrouget/servo,paulrouget/servo,peterjoel/servo,saneyuki/servo,DominoTree/servo,nnethercote/servo,paulrouget/servo,nnethercote/servo,mattnenterprise/servo,avadacatavra/servo,rnestler/servo,ConnorGBrewster/servo,SimonSapin/servo,anthgur/servo,emilio/servo,ConnorGBrewster/servo,rnestler/servo,canaltinova/servo,sadmansk/servo,avadacatavra/servo,mbrubeck/servo,upsuper/servo,cbrewster/servo,szeged/servo,nnethercote/servo,mbrubeck/servo,eddyb/servo,canaltinova/servo,dati91/servo,notriddle/servo,upsuper/servo,emilio/servo,CJ8664/servo,anthgur/servo,splav/servo,avadacatavra/servo,anthgur/servo,KiChjang/servo,peterjoel/servo,thiagopnts/servo,upsuper/servo,szeged/servo,DominoTree/servo,sadmansk/servo,KiChjang/servo,pyfisch/servo,pyfisch/servo,eddyb/servo,eddyb/servo,mattnenterprise/servo,CJ8664/servo,CJ8664/servo,splav/servo,fiji-flo/servo,dsandeephegde/servo,larsbergstrom/servo,mbrubeck/servo,CJ8664/servo,dsandeephegde/servo,peterjoel/servo,emilio/servo,nnethercote/servo,fiji-flo/servo,thiagopnts/servo,larsbergstrom/servo,peterjoel/servo,KiChjang/servo,splav/servo,thiagopnts/servo,upsuper/servo,mattnenterprise/servo,rnestler/servo,larsbergstrom/servo,mattnenterprise/servo,anthgur/servo,dati91/servo,mbrubeck/servo,larsbergstrom/servo,upsuper/servo,DominoTree/servo,emilio/servo,mattnenterprise/servo,nrc/servo,thiagopnts/servo,rnestler/servo,larsbergstrom/servo,anthgur/servo,upsuper/servo,nnethercote/servo,fiji-flo/servo,pyfisch/servo,nnethercote/servo,notriddle/servo,dati91/servo,jimberlage/servo,emilio/servo,pyfisch/servo,jimberlage/servo,anthgur/servo,cbrewster/servo,rnestler/servo,nrc/servo,eddyb/servo,fiji-flo/servo,ConnorGBrewster/servo,jimberlage/servo,avadacatavra/servo,sadmansk/servo,paulrouget/servo,szeged/servo,mbrubeck/servo,rnestler/servo,larsbergstrom/servo,dsandeephegde/servo,mattnenterprise/servo,splav/servo,nrc/servo,splav/servo,emilio/servo,nrc/servo,nnethercote/servo,paulrouget/servo,cbrewster/servo,dati91/servo,ConnorGBrewster/servo,CJ8664/servo,nrc/servo,jimberlage/servo,cbrewster/servo,notriddle/servo,peterjoel/servo,peterjoel/servo,DominoTree/servo,sadmansk/servo,pyfisch/servo,ConnorGBrewster/servo,eddyb/servo,anthgur/servo,mbrubeck/servo,dsandeephegde/servo,szeged/servo,eddyb/servo,dsandeephegde/servo,dsandeephegde/servo,nnethercote/servo,nrc/servo,larsbergstrom/servo,ConnorGBrewster/servo,eddyb/servo,dati91/servo,mbrubeck/servo,dati91/servo,SimonSapin/servo,jimberlage/servo,jimberlage/servo,pyfisch/servo,avadacatavra/servo,cbrewster/servo,canaltinova/servo,notriddle/servo,saneyuki/servo,peterjoel/servo,dsandeephegde/servo,ConnorGBrewster/servo,notriddle/servo,pyfisch/servo,saneyuki/servo,larsbergstrom/servo,sadmansk/servo,saneyuki/servo,paulrouget/servo,KiChjang/servo,peterjoel/servo,dati91/servo,SimonSapin/servo,CJ8664/servo,dati91/servo,saneyuki/servo,canaltinova/servo,DominoTree/servo,KiChjang/servo,SimonSapin/servo,splav/servo,paulrouget/servo,mattnenterprise/servo,upsuper/servo,avadacatavra/servo,upsuper/servo,notriddle/servo,DominoTree/servo,canaltinova/servo,canaltinova/servo,pyfisch/servo,rnestler/servo,szeged/servo,pyfisch/servo,paulrouget/servo,emilio/servo,larsbergstrom/servo,thiagopnts/servo,fiji-flo/servo,rnestler/servo,DominoTree/servo,szeged/servo,saneyuki/servo,nnethercote/servo,sadmansk/servo,splav/servo,fiji-flo/servo,DominoTree/servo,cbrewster/servo,canaltinova/servo,KiChjang/servo,saneyuki/servo,nrc/servo,szeged/servo,splav/servo,szeged/servo,canaltinova/servo,splav/servo,szeged/servo,larsbergstrom/servo,KiChjang/servo,fiji-flo/servo,saneyuki/servo,KiChjang/servo,SimonSapin/servo,thiagopnts/servo,avadacatavra/servo,cbrewster/servo,paulrouget/servo,KiChjang/servo,mbrubeck/servo,emilio/servo,peterjoel/servo,ConnorGBrewster/servo,cbrewster/servo,nnethercote/servo,SimonSapin/servo,eddyb/servo,anthgur/servo,notriddle/servo,szeged/servo,SimonSapin/servo,jimberlage/servo,CJ8664/servo,notriddle/servo,CJ8664/servo,sadmansk/servo,peterjoel/servo,mattnenterprise/servo,jimberlage/servo,DominoTree/servo,fiji-flo/servo,DominoTree/servo,emilio/servo,pyfisch/servo,sadmansk/servo,saneyuki/servo,jimberlage/servo,saneyuki/servo,notriddle/servo,paulrouget/servo,notriddle/servo,SimonSapin/servo,KiChjang/servo,emilio/servo,splav/servo,thiagopnts/servo,thiagopnts/servo