Remove repeated at in using.xml
Remove repeated at in using.xml

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