double-negate test for Stage1Only to fix `make clean`
double-negate test for Stage1Only to fix `make clean`

This was causing `utils/ghctags/dist-install` to not get removed
on `make clean` as `Stage1Only` was unset. So testing for `!= YES` is
less fragile than testing for `== NO` in this case.

Signed-off-by: Herbert Valerio Riedel <202fbcf3c00694524024feb79f3bb8fc1c4e4f9c@gnu.org>

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