ARM: Fix compile error for unw usage with clang-3.8
ARM: Fix compile error for unw usage with clang-3.8

This fix is also needed when using clang-3.8
Previous related patch is #4260

gkhanna79/coreclr,YongseopKim/coreclr,yeaicc/coreclr,bartdesmet/coreclr,kyulee1/coreclr,wateret/coreclr,josteink/coreclr,sejongoh/coreclr,ragmani/coreclr,dpodder/coreclr,dpodder/coreclr,poizan42/coreclr,yeaicc/coreclr,yeaicc/coreclr,bartonjs/coreclr,hseok-oh/coreclr,naamunds/coreclr,ZhichengZhu/coreclr,LLITCHEV/coreclr,gkhanna79/coreclr,yeaicc/coreclr,ragmani/coreclr,rartemev/coreclr,ruben-ayrapetyan/coreclr,cmckinsey/coreclr,shahid-pk/coreclr,cydhaselton/coreclr,dpodder/coreclr,naamunds/coreclr,schellap/coreclr,ragmani/coreclr,mskvortsov/coreclr,parjong/coreclr,vinnyrom/coreclr,dasMulli/coreclr,josteink/coreclr,josteink/coreclr,jamesqo/coreclr,russellhadley/coreclr,shahid-pk/coreclr,ramarag/coreclr,mmitche/coreclr,bartdesmet/coreclr,roncain/coreclr,wateret/coreclr,botaberg/coreclr,ruben-ayrapetyan/coreclr,JonHanna/coreclr,rartemev/coreclr,martinwoodward/coreclr,krytarowski/coreclr,martinwoodward/coreclr,JonHanna/coreclr,bartdesmet/coreclr,tijoytom/coreclr,gkhanna79/coreclr,botaberg/coreclr,tijoytom/coreclr,sagood/coreclr,AlexGhiondea/coreclr,cshung/coreclr,jhendrixMSFT/coreclr,Dmitry-Me/coreclr,JonHanna/coreclr,gkhanna79/coreclr,AlexGhiondea/coreclr,martinwoodward/coreclr,yizhang82/coreclr,ZhichengZhu/coreclr,parjong/coreclr,KrzysztofCwalina/coreclr,dpodder/coreclr,poizan42/coreclr,AlexGhiondea/coreclr,ZhichengZhu/coreclr,cmckinsey/coreclr,josteink/coreclr,poizan42/coreclr,manu-silicon/coreclr,martinwoodward/coreclr,qiudesong/coreclr,ruben-ayrapetyan/coreclr,ZhichengZhu/coreclr,shahid-pk/coreclr,kyulee1/coreclr,LLITCHEV/coreclr,ZhichengZhu/coreclr,mskvortsov/coreclr,neurospeech/coreclr,ragmani/coreclr,gkhanna79/coreclr,josteink/coreclr,jamesqo/coreclr,ramarag/coreclr,rartemev/coreclr,mskvortsov/coreclr,krk/coreclr,wtgodbe/coreclr,hseok-oh/coreclr,vinnyrom/coreclr,LLITCHEV/coreclr,sagood/coreclr,schellap/coreclr,bartdesmet/coreclr,kyulee1/coreclr,krk/coreclr,yizhang82/coreclr,vinnyrom/coreclr,mskvortsov/coreclr,mmitche/coreclr,hseok-oh/coreclr,martinwoodward/coreclr,KrzysztofCwalina/coreclr,jhendrixMSFT/coreclr,qiudesong/coreclr,sagood/coreclr,wtgodbe/coreclr,vinnyrom/coreclr,KrzysztofCwalina/coreclr,hseok-oh/coreclr,cmckinsey/coreclr,LLITCHEV/coreclr,pgavlin/coreclr,dasMulli/coreclr,yizhang82/coreclr,parjong/coreclr,YongseopKim/coreclr,manu-silicon/coreclr,yizhang82/coreclr,James-Ko/coreclr,josteink/coreclr,bartonjs/coreclr,cydhaselton/coreclr,sejongoh/coreclr,mmitche/coreclr,AlexGhiondea/coreclr,wtgodbe/coreclr,shahid-pk/coreclr,wtgodbe/coreclr,AlexGhiondea/coreclr,yeaicc/coreclr,YongseopKim/coreclr,krytarowski/coreclr,alexperovich/coreclr,KrzysztofCwalina/coreclr,russellhadley/coreclr,botaberg/coreclr,neurospeech/coreclr,cmckinsey/coreclr,jamesqo/coreclr,cmckinsey/coreclr,roncain/coreclr,jhendrixMSFT/coreclr,sjsinju/coreclr,Dmitry-Me/coreclr,roncain/coreclr,vinnyrom/coreclr,pgavlin/coreclr,JosephTremoulet/coreclr,krk/coreclr,schellap/coreclr,cydhaselton/coreclr,pgavlin/coreclr,tijoytom/coreclr,dasMulli/coreclr,cshung/coreclr,josteink/coreclr,martinwoodward/coreclr,alexperovich/coreclr,neurospeech/coreclr,naamunds/coreclr,kyulee1/coreclr,qiudesong/coreclr,bartdesmet/coreclr,vinnyrom/coreclr,alexperovich/coreclr,mmitche/coreclr,qiudesong/coreclr,KrzysztofCwalina/coreclr,krk/coreclr,naamunds/coreclr,bartonjs/coreclr,JosephTremoulet/coreclr,botaberg/coreclr,dasMulli/coreclr,jamesqo/coreclr,James-Ko/coreclr,qiudesong/coreclr,roncain/coreclr,bartonjs/coreclr,krk/coreclr,AlexGhiondea/coreclr,dpodder/coreclr,naamunds/coreclr,KrzysztofCwalina/coreclr,James-Ko/coreclr,vinnyrom/coreclr,jhendrixMSFT/coreclr,sagood/coreclr,mskvortsov/coreclr,JonHanna/coreclr,shahid-pk/coreclr,hseok-oh/coreclr,ruben-ayrapetyan/coreclr,roncain/coreclr,parjong/coreclr,LLITCHEV/coreclr,tijoytom/coreclr,cydhaselton/coreclr,russellhadley/coreclr,sjsinju/coreclr,yeaicc/coreclr,rartemev/coreclr,Dmitry-Me/coreclr,krytarowski/coreclr,manu-silicon/coreclr,JosephTremoulet/coreclr,parjong/coreclr,sejongoh/coreclr,ragmani/coreclr,ramarag/coreclr,poizan42/coreclr,kyulee1/coreclr,wateret/coreclr,James-Ko/coreclr,roncain/coreclr,poizan42/coreclr,jamesqo/coreclr,alexperovich/coreclr,tijoytom/coreclr,cshung/coreclr,manu-silicon/coreclr,yizhang82/coreclr,ramarag/coreclr,cshung/coreclr,bartdesmet/coreclr,russellhadley/coreclr,JosephTremoulet/coreclr,ragmani/coreclr,neurospeech/coreclr,sejongoh/coreclr,poizan42/coreclr,russellhadley/coreclr,JosephTremoulet/coreclr,LLITCHEV/coreclr,sjsinju/coreclr,Dmitry-Me/coreclr,botaberg/coreclr,bartonjs/coreclr,parjong/coreclr,dasMulli/coreclr,rartemev/coreclr,pgavlin/coreclr,wateret/coreclr,naamunds/coreclr,Dmitry-Me/coreclr,Dmitry-Me/coreclr,ruben-ayrapetyan/coreclr,krytarowski/coreclr,schellap/coreclr,cshung/coreclr,dasMulli/coreclr,ZhichengZhu/coreclr,dasMulli/coreclr,neurospeech/coreclr,sejongoh/coreclr,rartemev/coreclr,jamesqo/coreclr,cmckinsey/coreclr,Dmitry-Me/coreclr,KrzysztofCwalina/coreclr,bartdesmet/coreclr,YongseopKim/coreclr,cydhaselton/coreclr,russellhadley/coreclr,schellap/coreclr,YongseopKim/coreclr,cmckinsey/coreclr,pgavlin/coreclr,sejongoh/coreclr,bartonjs/coreclr,jhendrixMSFT/coreclr,manu-silicon/coreclr,bartonjs/coreclr,sejongoh/coreclr,alexperovich/coreclr,manu-silicon/coreclr,jhendrixMSFT/coreclr,wtgodbe/coreclr,hseok-oh/coreclr,yizhang82/coreclr,neurospeech/coreclr,YongseopKim/coreclr,krk/coreclr,dpodder/coreclr,ramarag/coreclr,ruben-ayrapetyan/coreclr,manu-silicon/coreclr,James-Ko/coreclr,cydhaselton/coreclr,schellap/coreclr,ramarag/coreclr,shahid-pk/coreclr,mmitche/coreclr,wateret/coreclr,kyulee1/coreclr,mmitche/coreclr,krytarowski/coreclr,tijoytom/coreclr,James-Ko/coreclr,cshung/coreclr,LLITCHEV/coreclr,gkhanna79/coreclr,pgavlin/coreclr,ramarag/coreclr,JonHanna/coreclr,wtgodbe/coreclr,JonHanna/coreclr,roncain/coreclr,sjsinju/coreclr,sjsinju/coreclr,alexperovich/coreclr,botaberg/coreclr,shahid-pk/coreclr,ZhichengZhu/coreclr,sagood/coreclr,mskvortsov/coreclr,sagood/coreclr,schellap/coreclr,krytarowski/coreclr,naamunds/coreclr,qiudesong/coreclr,wateret/coreclr,martinwoodward/coreclr,JosephTremoulet/coreclr,jhendrixMSFT/coreclr,sjsinju/coreclr,yeaicc/coreclr