ignore non-existent mount points in readHugePageSizes
ignore non-existent mount points in readHugePageSizes

Summary:
Some of mount points may not exist (for example, if
application is running from chroot and unshare hasn't been used).

@override-unit-failures

Test Plan: unicorn canary

Reviewed By: tudorb@fb.com

FB internal diff: D1311374


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