Only disable nullable warnings for mult-targeted projects
Only disable nullable warnings for mult-targeted projects

sharwell/roslyn,dotnet/roslyn,KevinRansom/roslyn,physhi/roslyn,genlu/roslyn,panopticoncentral/roslyn,sharwell/roslyn,jmarolf/roslyn,bartdesmet/roslyn,wvdd007/roslyn,bartdesmet/roslyn,CyrusNajmabadi/roslyn,AmadeusW/roslyn,tannergooding/roslyn,aelij/roslyn,genlu/roslyn,tmat/roslyn,AlekseyTs/roslyn,AmadeusW/roslyn,sharwell/roslyn,mgoertz-msft/roslyn,shyamnamboodiripad/roslyn,weltkante/roslyn,KirillOsenkov/roslyn,CyrusNajmabadi/roslyn,physhi/roslyn,ErikSchierboom/roslyn,genlu/roslyn,eriawan/roslyn,ErikSchierboom/roslyn,eriawan/roslyn,mgoertz-msft/roslyn,shyamnamboodiripad/roslyn,KevinRansom/roslyn,gafter/roslyn,KevinRansom/roslyn,mavasani/roslyn,jasonmalinowski/roslyn,dotnet/roslyn,mavasani/roslyn,jasonmalinowski/roslyn,weltkante/roslyn,physhi/roslyn,KirillOsenkov/roslyn,gafter/roslyn,jmarolf/roslyn,aelij/roslyn,panopticoncentral/roslyn,tmat/roslyn,wvdd007/roslyn,tmat/roslyn,KirillOsenkov/roslyn,ErikSchierboom/roslyn,diryboy/roslyn,stephentoub/roslyn,heejaechang/roslyn,mavasani/roslyn,CyrusNajmabadi/roslyn,mgoertz-msft/roslyn,jmarolf/roslyn,stephentoub/roslyn,heejaechang/roslyn,stephentoub/roslyn,bartdesmet/roslyn,aelij/roslyn,jasonmalinowski/roslyn,brettfo/roslyn,gafter/roslyn,diryboy/roslyn,wvdd007/roslyn,panopticoncentral/roslyn,AlekseyTs/roslyn,brettfo/roslyn,tannergooding/roslyn,weltkante/roslyn,shyamnamboodiripad/roslyn,eriawan/roslyn,AlekseyTs/roslyn,AmadeusW/roslyn,heejaechang/roslyn,tannergooding/roslyn,dotnet/roslyn,diryboy/roslyn,brettfo/roslyn