Replace file existence check of $(IbcMergePath) with an empty property check
Replace file existence check of $(IbcMergePath) with an empty property check

aelij/roslyn,amcasey/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,CaptainHayashi/roslyn,jeffanders/roslyn,shyamnamboodiripad/roslyn,CaptainHayashi/roslyn,TyOverby/roslyn,CyrusNajmabadi/roslyn,ErikSchierboom/roslyn,diryboy/roslyn,sharwell/roslyn,jkotas/roslyn,davkean/roslyn,dotnet/roslyn,abock/roslyn,pdelvo/roslyn,lorcanmooney/roslyn,CaptainHayashi/roslyn,orthoxerox/roslyn,tmat/roslyn,mattscheffer/roslyn,jkotas/roslyn,AmadeusW/roslyn,jmarolf/roslyn,MattWindsor91/roslyn,yeaicc/roslyn,AlekseyTs/roslyn,AnthonyDGreen/roslyn,bkoelman/roslyn,zooba/roslyn,cston/roslyn,zooba/roslyn,swaroop-sridhar/roslyn,VSadov/roslyn,orthoxerox/roslyn,akrisiun/roslyn,AmadeusW/roslyn,DustinCampbell/roslyn,wvdd007/roslyn,srivatsn/roslyn,physhi/roslyn,KevinRansom/roslyn,nguerrera/roslyn,tvand7093/roslyn,Hosch250/roslyn,physhi/roslyn,pdelvo/roslyn,agocke/roslyn,yeaicc/roslyn,VSadov/roslyn,AlekseyTs/roslyn,mattwar/roslyn,mavasani/roslyn,srivatsn/roslyn,orthoxerox/roslyn,jkotas/roslyn,brettfo/roslyn,VSadov/roslyn,mattwar/roslyn,weltkante/roslyn,dpoeschl/roslyn,jamesqo/roslyn,reaction1989/roslyn,Giftednewt/roslyn,aelij/roslyn,tvand7093/roslyn,yeaicc/roslyn,mgoertz-msft/roslyn,amcasey/roslyn,bartdesmet/roslyn,Hosch250/roslyn,jamesqo/roslyn,OmarTawfik/roslyn,reaction1989/roslyn,robinsedlaczek/roslyn,gafter/roslyn,genlu/roslyn,cston/roslyn,Giftednewt/roslyn,swaroop-sridhar/roslyn,khyperia/roslyn,TyOverby/roslyn,TyOverby/roslyn,Hosch250/roslyn,bartdesmet/roslyn,mattscheffer/roslyn,jeffanders/roslyn,OmarTawfik/roslyn,dpoeschl/roslyn,Giftednewt/roslyn,kelltrick/roslyn,jeffanders/roslyn,eriawan/roslyn,jasonmalinowski/roslyn,tannergooding/roslyn,dpoeschl/roslyn,MattWindsor91/roslyn,mgoertz-msft/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,akrisiun/roslyn,jcouv/roslyn,bartdesmet/roslyn,davkean/roslyn,mattwar/roslyn,weltkante/roslyn,MattWindsor91/roslyn,DustinCampbell/roslyn,davkean/roslyn,MattWindsor91/roslyn,gafter/roslyn,amcasey/roslyn,DustinCampbell/roslyn,stephentoub/roslyn,gafter/roslyn,panopticoncentral/roslyn,eriawan/roslyn,AlekseyTs/roslyn,MichalStrehovsky/roslyn,KevinRansom/roslyn,jasonmalinowski/roslyn,swaroop-sridhar/roslyn,jcouv/roslyn,cston/roslyn,mmitche/roslyn,khyperia/roslyn,mattscheffer/roslyn,tannergooding/roslyn,jmarolf/roslyn,ErikSchierboom/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,jcouv/roslyn,genlu/roslyn,nguerrera/roslyn,KevinRansom/roslyn,akrisiun/roslyn,mavasani/roslyn,brettfo/roslyn,tannergooding/roslyn,sharwell/roslyn,diryboy/roslyn,KirillOsenkov/roslyn,OmarTawfik/roslyn,tmeschter/roslyn,MichalStrehovsky/roslyn,AnthonyDGreen/roslyn,panopticoncentral/roslyn,srivatsn/roslyn,tmeschter/roslyn,khyperia/roslyn,xasx/roslyn,KirillOsenkov/roslyn,reaction1989/roslyn,KirillOsenkov/roslyn,zooba/roslyn,mgoertz-msft/roslyn,heejaechang/roslyn,bkoelman/roslyn,kelltrick/roslyn,eriawan/roslyn,agocke/roslyn,AmadeusW/roslyn,tmeschter/roslyn,heejaechang/roslyn,tvand7093/roslyn,wvdd007/roslyn,abock/roslyn,drognanar/roslyn,weltkante/roslyn,jasonmalinowski/roslyn,bkoelman/roslyn,dotnet/roslyn,AnthonyDGreen/roslyn,abock/roslyn,robinsedlaczek/roslyn,heejaechang/roslyn,pdelvo/roslyn,agocke/roslyn,jmarolf/roslyn,tmat/roslyn,drognanar/roslyn,lorcanmooney/roslyn,wvdd007/roslyn,mavasani/roslyn,sharwell/roslyn,paulvanbrenk/roslyn,paulvanbrenk/roslyn,tmat/roslyn,lorcanmooney/roslyn,jamesqo/roslyn,physhi/roslyn,stephentoub/roslyn,CyrusNajmabadi/roslyn,xasx/roslyn,CyrusNajmabadi/roslyn,mmitche/roslyn,kelltrick/roslyn,diryboy/roslyn,stephentoub/roslyn,dotnet/roslyn,xasx/roslyn,shyamnamboodiripad/roslyn,paulvanbrenk/roslyn,brettfo/roslyn,shyamnamboodiripad/roslyn,nguerrera/roslyn,drognanar/roslyn,ErikSchierboom/roslyn,MichalStrehovsky/roslyn,robinsedlaczek/roslyn,mmitche/roslyn,genlu/roslyn,aelij/roslyn,panopticoncentral/roslyn