strerror_r is XSI compliant on Apple/FreeBSD
strerror_r is XSI compliant on Apple/FreeBSD

Summary:
- Noticed this due to an -fpermissive compiler warning while compiling
HHVM for OSX (complaint of trying to cast int to char*)

Test Plan:
- Compiled
- Confirmed the build warning is fixed by this on the Mac OS X build

Reviewed By: tudorb@fb.com

FB internal diff: D865169

romange/folly,reddit/folly,nickhen/folly,leolujuyi/folly,stonegithubs/folly,brunomorishita/folly,Orvid/folly,floxard/folly,brunomorishita/folly,nickhen/folly,theiver9827/folly,alexst07/folly,stonegithubs/folly,kernelim/folly,bobegir/folly,rklabs/folly,cole14/folly,clearlinux/folly,fw1121/folly,floxard/folly,guker/folly,SammyK/folly,bobegir/folly,charsyam/folly,PoisonBOx/folly,fw1121/folly,Eagle-X/folly,sonnyhu/folly,Hincoin/folly,clearlylin/folly,SammyK/folly,cppfool/folly,ykarlsbrun/folly,gaoyingie/folly,gaoyingie/folly,kernelim/folly,PoisonBOx/folly,KSreeHarsha/folly,yangjin-unique/folly,loverszhaokai/folly,Orvid/folly,juniway/folly,PPC64/folly,xzmagic/folly,clearlinux/folly,bikong2/folly,renyinew/folly,KSreeHarsha/folly,PoisonBOx/folly,constantine001/folly,gaoyingie/folly,nickhen/folly,bowlofstew/folly,sonnyhu/folly,reddit/folly,charsyam/folly,constantine001/folly,bsampath/folly,charsyam/folly,upsoft/folly,shaobz/folly,loversInJapan/folly,project-zerus/folly,wildinto/folly,SeanRBurton/folly,constantine001/folly,cppfool/folly,tomhughes/folly,bsampath/folly,zhiweicai/folly,bsampath/folly,theiver9827/folly,chjp2046/folly,chjp2046/folly,colemancda/folly,clearlinux/folly,fw1121/folly,raphaelamorim/folly,facebook/folly,guker/folly,hongliangzhao/folly,clearlylin/folly,clearlylin/folly,kernelim/folly,cppfool/folly,nickhen/folly,lifei/folly,Orvid/folly,zhiweicai/folly,xzmagic/folly,Eagle-X/folly,upsoft/folly,cole14/folly,lifei/folly,Eagle-X/folly,stonegithubs/folly,CJstar/folly,brunomorishita/folly,sakishum/folly,hongliangzhao/folly,renyinew/folly,SeanRBurton/folly,facebook/folly,arg0/folly,renyinew/folly,bsampath/folly,Orvid/folly,loverszhaokai/folly,doctaweeks/folly,sonnyhu/folly,leolujuyi/folly,CJstar/folly,gavioto/folly,loversInJapan/folly,yangjin-unique/folly,arg0/folly,colemancda/folly,KSreeHarsha/folly,rklabs/folly,PPC64/folly,CJstar/folly,alexst07/folly,theiver9827/folly,SammyK/folly,SammyK/folly,clearlinux/folly,lifei/folly,KSreeHarsha/folly,juniway/folly,chjp2046/folly,unmeshvrije/C--,cppfool/folly,yangjin-unique/folly,rklabs/folly,unmeshvrije/C--,zhiweicai/folly,upsoft/folly,yangjin-unique/folly,doctaweeks/folly,raphaelamorim/folly,alexst07/folly,kernelim/folly,project-zerus/folly,mqeizi/folly,PoisonBOx/folly,nickhen/folly,CJstar/folly,ykarlsbrun/folly,Eagle-X/folly,tomhughes/folly,tempbottle/folly,mqeizi/folly,tempbottle/folly,gaoyingie/folly,bobegir/folly,doctaweeks/folly,clearlylin/folly,tomhughes/folly,rklabs/folly,floxard/folly,stonegithubs/folly,juniway/folly,project-zerus/folly,yangjin-unique/folly,xzmagic/folly,sakishum/folly,renyinew/folly,floxard/folly,wildinto/folly,shaobz/folly,KSreeHarsha/folly,hongliangzhao/folly,lifei/folly,PoisonBOx/folly,doctaweeks/folly,Hincoin/folly,leolujuyi/folly,PPC64/folly,raphaelamorim/folly,charsyam/folly,cole14/folly,doctaweeks/folly,guker/folly,fw1121/folly,bobegir/folly,mqeizi/folly,bowlofstew/folly,Hincoin/folly,fw1121/folly,unmeshvrije/C--,romange/folly,project-zerus/folly,upsoft/folly,bikong2/folly,gavioto/folly,sakishum/folly,loversInJapan/folly,zhiweicai/folly,brunomorishita/folly,theiver9827/folly,PPC64/folly,guker/folly,arg0/folly,arg0/folly,tempbottle/folly,unmeshvrije/C--,tempbottle/folly,unmeshvrije/C--,reddit/folly,floxard/folly,wildinto/folly,hongliangzhao/folly,arg0/folly,unmeshvrije/C--,guker/folly,romange/folly,Orvid/folly,zhiweicai/folly,brunomorishita/folly,facebook/folly,tomhughes/folly,loverszhaokai/folly,colemancda/folly,cole14/folly,loverszhaokai/folly,xzmagic/folly,Hincoin/folly,raphaelamorim/folly,leolujuyi/folly,tempbottle/folly,hongliangzhao/folly,loversInJapan/folly,facebook/folly,wildinto/folly,xzmagic/folly,colemancda/folly,ykarlsbrun/folly,bowlofstew/folly,sakishum/folly,constantine001/folly,alexst07/folly,clearlinux/folly,cole14/folly,bsampath/folly,bikong2/folly,tomhughes/folly,project-zerus/folly,sonnyhu/folly,gavioto/folly,mqeizi/folly,bowlofstew/folly,loverszhaokai/folly,wildinto/folly,clearlylin/folly,cppfool/folly,upsoft/folly,reddit/folly,bikong2/folly,chjp2046/folly,bowlofstew/folly,gaoyingie/folly,stonegithubs/folly,SeanRBurton/folly,lifei/folly,leolujuyi/folly,colemancda/folly,shaobz/folly,chjp2046/folly,rklabs/folly,theiver9827/folly,shaobz/folly,kernelim/folly,sakishum/folly,gavioto/folly,PPC64/folly,facebook/folly,SeanRBurton/folly,loversInJapan/folly,SeanRBurton/folly,mqeizi/folly,SammyK/folly,Eagle-X/folly,bikong2/folly,ykarlsbrun/folly,bobegir/folly,reddit/folly,raphaelamorim/folly,shaobz/folly,juniway/folly,ykarlsbrun/folly,Hincoin/folly,renyinew/folly,constantine001/folly,gavioto/folly,romange/folly,alexst07/folly,sonnyhu/folly,CJstar/folly,romange/folly,juniway/folly