Remove missing archs (mipseb, mipsel, alpha) (#5734)
Remove missing archs (mipseb, mipsel, alpha) (#5734)

It doesn't hurt to map these to ArchUnknown since we don't need to
know anything specific about them, and adding them would be a pain
(there are a bunch of places where we have to case-match on all the
arches to avoid warnings).

olsner/ghc,oldmanmike/ghc,AlexanderPankiv/ghc,AlexanderPankiv/ghc,vikraman/ghc,GaloisInc/halvm-ghc,snoyberg/ghc,ezyang/ghc,ryantm/ghc,vikraman/ghc,lukexi/ghc-7.8-arm64,shlevy/ghc,sgillespie/ghc,tibbe/ghc,lukexi/ghc,ekmett/ghc,gcampax/ghc,ghc-android/ghc,anton-dessiatov/ghc,tjakway/ghcjvm,green-haskell/ghc,spacekitteh/smcghc,sdiehl/ghc,nomeata/ghc,hferreiro/replay,TomMD/ghc,da-x/ghc,snoyberg/ghc,shlevy/ghc,gridaphobe/ghc,hferreiro/replay,urbanslug/ghc,forked-upstream-packages-for-ghcjs/ghc,ezyang/ghc,gcampax/ghc,ezyang/ghc,elieux/ghc,olsner/ghc,nkaretnikov/ghc,ml9951/ghc,mcschroeder/ghc,nomeata/ghc,mfine/ghc,nathyong/microghc-ghc,urbanslug/ghc,forked-upstream-packages-for-ghcjs/ghc,siddhanathan/ghc,ghc-android/ghc,nkaretnikov/ghc,nathyong/microghc-ghc,green-haskell/ghc,nushio3/ghc,snoyberg/ghc,anton-dessiatov/ghc,anton-dessiatov/ghc,christiaanb/ghc,wxwxwwxxx/ghc,hferreiro/replay,nushio3/ghc,tibbe/ghc,acowley/ghc,tjakway/ghcjvm,fmthoma/ghc,holzensp/ghc,gridaphobe/ghc,mfine/ghc,sdiehl/ghc,spacekitteh/smcghc,ml9951/ghc,mettekou/ghc,jstolarek/ghc,fmthoma/ghc,christiaanb/ghc,GaloisInc/halvm-ghc,mcschroeder/ghc,bitemyapp/ghc,ghc-android/ghc,nkaretnikov/ghc,mfine/ghc,nkaretnikov/ghc,gcampax/ghc,ezyang/ghc,urbanslug/ghc,TomMD/ghc,vTurbine/ghc,tibbe/ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,ryantm/ghc,TomMD/ghc,tjakway/ghcjvm,nathyong/microghc-ghc,ml9951/ghc,oldmanmike/ghc,ghc-android/ghc,hferreiro/replay,vTurbine/ghc,wxwxwwxxx/ghc,gridaphobe/ghc,acowley/ghc,shlevy/ghc,da-x/ghc,lukexi/ghc,mcschroeder/ghc,oldmanmike/ghc,nkaretnikov/ghc,oldmanmike/ghc,gcampax/ghc,gridaphobe/ghc,green-haskell/ghc,frantisekfarka/ghc-dsi,nushio3/ghc,sdiehl/ghc,ryantm/ghc,olsner/ghc,spacekitteh/smcghc,snoyberg/ghc,vikraman/ghc,wxwxwwxxx/ghc,urbanslug/ghc,ml9951/ghc,siddhanathan/ghc,vTurbine/ghc,hferreiro/replay,ryantm/ghc,ekmett/ghc,holzensp/ghc,forked-upstream-packages-for-ghcjs/ghc,bitemyapp/ghc,nushio3/ghc,holzensp/ghc,urbanslug/ghc,mcschroeder/ghc,gcampax/ghc,forked-upstream-packages-for-ghcjs/ghc,olsner/ghc,nomeata/ghc,forked-upstream-packages-for-ghcjs/ghc,TomMD/ghc,ghc-android/ghc,nomeata/ghc,mettekou/ghc,siddhanathan/ghc,siddhanathan/ghc,vikraman/ghc,gcampax/ghc,fmthoma/ghc,siddhanathan/ghc,holzensp/ghc,nushio3/ghc,AlexanderPankiv/ghc,ml9951/ghc,gcampax/ghc,ekmett/ghc,holzensp/ghc,sgillespie/ghc,GaloisInc/halvm-ghc,elieux/ghc,bitemyapp/ghc,shlevy/ghc,nathyong/microghc-ghc,anton-dessiatov/ghc,elieux/ghc,ml9951/ghc,shlevy/ghc,tibbe/ghc,hferreiro/replay,snoyberg/ghc,sdiehl/ghc,ghc-android/ghc,sdiehl/ghc,lukexi/ghc-7.8-arm64,elieux/ghc,vikraman/ghc,acowley/ghc,mcschroeder/ghc,shlevy/ghc,christiaanb/ghc,olsner/ghc,forked-upstream-packages-for-ghcjs/ghc,sgillespie/ghc,mfine/ghc,green-haskell/ghc,elieux/ghc,fmthoma/ghc,ezyang/ghc,ekmett/ghc,nushio3/ghc,lukexi/ghc,gridaphobe/ghc,GaloisInc/halvm-ghc,lukexi/ghc,jstolarek/ghc,nathyong/microghc-ghc,ezyang/ghc,wxwxwwxxx/ghc,vTurbine/ghc,christiaanb/ghc,da-x/ghc,ghc-android/ghc,sgillespie/ghc,mettekou/ghc,acowley/ghc,urbanslug/ghc,tjakway/ghcjvm,wxwxwwxxx/ghc,ryantm/ghc,frantisekfarka/ghc-dsi,olsner/ghc,mettekou/ghc,christiaanb/ghc,frantisekfarka/ghc-dsi,fmthoma/ghc,spacekitteh/smcghc,vikraman/ghc,wxwxwwxxx/ghc,mfine/ghc,elieux/ghc,TomMD/ghc,lukexi/ghc-7.8-arm64,nkaretnikov/ghc,TomMD/ghc,anton-dessiatov/ghc,acowley/ghc,AlexanderPankiv/ghc,christiaanb/ghc,siddhanathan/ghc,AlexanderPankiv/ghc,ml9951/ghc,sgillespie/ghc,GaloisInc/halvm-ghc,nomeata/ghc,green-haskell/ghc,frantisekfarka/ghc-dsi,gridaphobe/ghc,AlexanderPankiv/ghc,da-x/ghc,vTurbine/ghc,oldmanmike/ghc,mfine/ghc,vTurbine/ghc,lukexi/ghc,mcschroeder/ghc,wxwxwwxxx/ghc,TomMD/ghc,lukexi/ghc-7.8-arm64,olsner/ghc,tibbe/ghc,tjakway/ghcjvm,tjakway/ghcjvm,sdiehl/ghc,ml9951/ghc,nathyong/microghc-ghc,hferreiro/replay,vTurbine/ghc,bitemyapp/ghc,ekmett/ghc,AlexanderPankiv/ghc,da-x/ghc,mettekou/ghc,acowley/ghc,fmthoma/ghc,jstolarek/ghc,mettekou/ghc,oldmanmike/ghc,siddhanathan/ghc,mfine/ghc,gridaphobe/ghc,fmthoma/ghc,ezyang/ghc,christiaanb/ghc,spacekitteh/smcghc,GaloisInc/halvm-ghc,nkaretnikov/ghc,lukexi/ghc-7.8-arm64,da-x/ghc,frantisekfarka/ghc-dsi,sdiehl/ghc,elieux/ghc,sgillespie/ghc,acowley/ghc,vikraman/ghc,GaloisInc/halvm-ghc,da-x/ghc,tjakway/ghcjvm,oldmanmike/ghc,snoyberg/ghc,snoyberg/ghc,sgillespie/ghc,urbanslug/ghc,shlevy/ghc,jstolarek/ghc,anton-dessiatov/ghc,mcschroeder/ghc,mettekou/ghc,bitemyapp/ghc,jstolarek/ghc,nushio3/ghc,anton-dessiatov/ghc