Fix Stage1Only: don't build ghctags.
Fix Stage1Only: don't build ghctags.

ghctags needs the stage2 compiler, since it uses the GHC API.

Fixes #8126.

Authored-by: Stephen Blackheath <6eae3a5b062c6d0d79f070c26e6d62486b40cb46@blacksapphire.com>
Signed-off-by: Austin Seipp <48c905ac3851f382b914247d97dd93273d5ff555@pobox.com>

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