[trivial] Make namespace explicit for is_regular_file
[trivial] Make namespace explicit for is_regular_file

is_regular_file resolves using argument dependent lookup. Make the
namespace explicit so it's obvious where the function is defined.

sebrandon1/bitcoin,rnicoll/bitcoin,vmp32k/litecoin,ryanofsky/bitcoin,myriadcoin/myriadcoin,domob1812/huntercore,TheBlueMatt/bitcoin,ajtowns/bitcoin,Christewart/bitcoin,myriadcoin/myriadcoin,Kogser/bitcoin,ajtowns/bitcoin,mm-s/bitcoin,paveljanik/bitcoin,afk11/bitcoin,jnewbery/bitcoin,laudaa/bitcoin,lbryio/lbrycrd,instagibbs/bitcoin,jambolo/bitcoin,laudaa/bitcoin,bitcoinknots/bitcoin,tecnovert/particl-core,kazcw/bitcoin,stamhe/bitcoin,GroestlCoin/GroestlCoin,apoelstra/bitcoin,mruddy/bitcoin,tecnovert/particl-core,MeshCollider/bitcoin,Bushstar/UFO-Project,1185/starwels,sipsorcery/bitcoin,kallewoof/bitcoin,anditto/bitcoin,ryanofsky/bitcoin,cdecker/bitcoin,lateminer/bitcoin,Christewart/bitcoin,jtimon/bitcoin,yenliangl/bitcoin,deeponion/deeponion,practicalswift/bitcoin,anditto/bitcoin,pstratem/bitcoin,rnicoll/dogecoin,1185/starwels,yenliangl/bitcoin,maaku/bitcoin,ajtowns/bitcoin,donaloconnor/bitcoin,apoelstra/bitcoin,randy-waterhouse/bitcoin,sipsorcery/bitcoin,apoelstra/bitcoin,GroestlCoin/bitcoin,droark/bitcoin,qtumproject/qtum,EthanHeilman/bitcoin,RHavar/bitcoin,ahmedbodi/vertcoin,droark/bitcoin,MarcoFalke/bitcoin,ajtowns/bitcoin,jamesob/bitcoin,MarcoFalke/bitcoin,mruddy/bitcoin,lateminer/bitcoin,anditto/bitcoin,digibyte/digibyte,maaku/bitcoin,yenliangl/bitcoin,viacoin/viacoin,vertcoin/vertcoin,n1bor/bitcoin,globaltoken/globaltoken,AkioNak/bitcoin,mm-s/bitcoin,joshrabinowitz/bitcoin,OmniLayer/omnicore,Xekyo/bitcoin,alecalve/bitcoin,mitchellcash/bitcoin,1185/starwels,laudaa/bitcoin,jamesob/bitcoin,tecnovert/particl-core,domob1812/namecore,JeremyRubin/bitcoin,MeshCollider/bitcoin,bitcoinsSG/bitcoin,kallewoof/bitcoin,Christewart/bitcoin,pstratem/bitcoin,BTCGPU/BTCGPU,mitchellcash/bitcoin,GlobalBoost/GlobalBoost,RHavar/bitcoin,myriadteam/myriadcoin,brandonrobertz/namecoin-core,laudaa/bitcoin,vmp32k/litecoin,domob1812/bitcoin,alecalve/bitcoin,tecnovert/particl-core,namecoin/namecoin-core,ajtowns/bitcoin,RHavar/bitcoin,RHavar/bitcoin,mm-s/bitcoin,namecoin/namecore,peercoin/peercoin,donaloconnor/bitcoin,rnicoll/bitcoin,apoelstra/bitcoin,qtumproject/qtum,r8921039/bitcoin,Xekyo/bitcoin,vertcoin/vertcoin,Flowdalic/bitcoin,rawodb/bitcoin,qtumproject/qtum,GroestlCoin/bitcoin,bitcoinsSG/bitcoin,Bushstar/UFO-Project,bitcoin/bitcoin,bespike/litecoin,bitcoinknots/bitcoin,untrustbank/litecoin,myriadteam/myriadcoin,Christewart/bitcoin,domob1812/namecore,jnewbery/bitcoin,jamesob/bitcoin,jlopp/statoshi,litecoin-project/litecoin,ppcoin/ppcoin,Flowdalic/bitcoin,litecoin-project/litecoin,TheBlueMatt/bitcoin,jamesob/bitcoin,GroestlCoin/GroestlCoin,FeatherCoin/Feathercoin,particl/particl-core,droark/bitcoin,Christewart/bitcoin,qtumproject/qtum,pstratem/bitcoin,Flowdalic/bitcoin,fujicoin/fujicoin,MarcoFalke/bitcoin,paveljanik/bitcoin,OmniLayer/omnicore,sstone/bitcoin,fanquake/bitcoin,anditto/bitcoin,Bushstar/UFO-Project,domob1812/huntercore,fujicoin/fujicoin,mruddy/bitcoin,fanquake/bitcoin,namecoin/namecoin-core,rnicoll/dogecoin,nikkitan/bitcoin,AkioNak/bitcoin,jamesob/bitcoin,mm-s/bitcoin,MazaCoin/maza,andreaskern/bitcoin,mruddy/bitcoin,jnewbery/bitcoin,gjhiggins/vcoincore,andreaskern/bitcoin,mb300sd/bitcoin,Xekyo/bitcoin,r8921039/bitcoin,domob1812/bitcoin,MeshCollider/bitcoin,CryptArc/bitcoin,myriadcoin/myriadcoin,maaku/bitcoin,kallewoof/bitcoin,midnightmagic/bitcoin,sipsorcery/bitcoin,sstone/bitcoin,peercoin/peercoin,starwels/starwels,Sjors/bitcoin,FeatherCoin/Feathercoin,starwels/starwels,randy-waterhouse/bitcoin,maaku/bitcoin,sebrandon1/bitcoin,Kogser/bitcoin,paveljanik/bitcoin,prusnak/bitcoin,Sjors/bitcoin,TheBlueMatt/bitcoin,apoelstra/bitcoin,domob1812/namecore,gjhiggins/vcoincore,ElementsProject/elements,ppcoin/ppcoin,BTCGPU/BTCGPU,sebrandon1/bitcoin,practicalswift/bitcoin,prusnak/bitcoin,Xekyo/bitcoin,Kogser/bitcoin,bitcoinsSG/bitcoin,alecalve/bitcoin,cryptoprojects/ultimateonlinecash,TheBlueMatt/bitcoin,particl/particl-core,laudaa/bitcoin,donaloconnor/bitcoin,namecoin/namecore,gjhiggins/vcoincore,cdecker/bitcoin,mb300sd/bitcoin,afk11/bitcoin,vmp32k/litecoin,litecoin-project/litecoin,GroestlCoin/bitcoin,myriadteam/myriadcoin,pataquets/namecoin-core,h4x3rotab/BTCGPU,guncoin/guncoin,bitcoinsSG/bitcoin,bitcoinknots/bitcoin,Kogser/bitcoin,stamhe/bitcoin,JeremyRubin/bitcoin,brandonrobertz/namecoin-core,mitchellcash/bitcoin,rawodb/bitcoin,CryptArc/bitcoin,ryanofsky/bitcoin,kazcw/bitcoin,myriadteam/myriadcoin,peercoin/peercoin,donaloconnor/bitcoin,MeshCollider/bitcoin,AkioNak/bitcoin,jnewbery/bitcoin,dscotese/bitcoin,fujicoin/fujicoin,mb300sd/bitcoin,jtimon/bitcoin,randy-waterhouse/bitcoin,Bushstar/UFO-Project,andreaskern/bitcoin,myriadteam/myriadcoin,mb300sd/bitcoin,MeshCollider/bitcoin,mitchellcash/bitcoin,rnicoll/bitcoin,ahmedbodi/vertcoin,Bushstar/UFO-Project,pataquets/namecoin-core,OmniLayer/omnicore,viacoin/viacoin,jtimon/bitcoin,thrasher-/litecoin,tjps/bitcoin,jmcorgan/bitcoin,lbryio/lbrycrd,alecalve/bitcoin,fanquake/bitcoin,particl/particl-core,joshrabinowitz/bitcoin,tecnovert/particl-core,AkioNak/bitcoin,instagibbs/bitcoin,domob1812/bitcoin,domob1812/huntercore,Kogser/bitcoin,nikkitan/bitcoin,untrustbank/litecoin,randy-waterhouse/bitcoin,ElementsProject/elements,midnightmagic/bitcoin,ppcoin/ppcoin,namecoin/namecoin-core,n1bor/bitcoin,cryptoprojects/ultimateonlinecash,ericshawlinux/bitcoin,kazcw/bitcoin,jonasschnelli/bitcoin,Rav3nPL/bitcoin,ppcoin/ppcoin,joshrabinowitz/bitcoin,domob1812/huntercore,MazaCoin/maza,droark/bitcoin,myriadcoin/myriadcoin,digibyte/digibyte,DigitalPandacoin/pandacoin,brandonrobertz/namecoin-core,tjps/bitcoin,FeatherCoin/Feathercoin,cryptoprojects/ultimateonlinecash,ryanofsky/bitcoin,Kogser/bitcoin,GlobalBoost/GlobalBoost,particl/particl-core,h4x3rotab/BTCGPU,prusnak/bitcoin,lbryio/lbrycrd,rawodb/bitcoin,stamhe/bitcoin,vertcoin/vertcoin,andreaskern/bitcoin,tjps/bitcoin,starwels/starwels,h4x3rotab/BTCGPU,myriadteam/myriadcoin,GroestlCoin/GroestlCoin,domob1812/namecore,fujicoin/fujicoin,monacoinproject/monacoin,randy-waterhouse/bitcoin,bespike/litecoin,wellenreiter01/Feathercoin,DigitalPandacoin/pandacoin,guncoin/guncoin,dscotese/bitcoin,GroestlCoin/bitcoin,RHavar/bitcoin,apoelstra/bitcoin,jlopp/statoshi,jonasschnelli/bitcoin,laudaa/bitcoin,domob1812/bitcoin,rnicoll/bitcoin,cdecker/bitcoin,digibyte/digibyte,practicalswift/bitcoin,nikkitan/bitcoin,CryptArc/bitcoin,globaltoken/globaltoken,namecoin/namecoin-core,namecoin/namecore,prusnak/bitcoin,viacoin/viacoin,AkioNak/bitcoin,DigitalPandacoin/pandacoin,rnicoll/dogecoin,globaltoken/globaltoken,yenliangl/bitcoin,ericshawlinux/bitcoin,jlopp/statoshi,andreaskern/bitcoin,ahmedbodi/vertcoin,bitcoin/bitcoin,digibyte/digibyte,fujicoin/fujicoin,Kogser/bitcoin,jambolo/bitcoin,donaloconnor/bitcoin,namecoin/namecore,GroestlCoin/GroestlCoin,jambolo/bitcoin,domob1812/bitcoin,OmniLayer/omnicore,sstone/bitcoin,ericshawlinux/bitcoin,joshrabinowitz/bitcoin,Bushstar/UFO-Project,Rav3nPL/bitcoin,r8921039/bitcoin,qtumproject/qtum,GlobalBoost/GlobalBoost,ElementsProject/elements,sebrandon1/bitcoin,1185/starwels,thrasher-/litecoin,Christewart/bitcoin,n1bor/bitcoin,CryptArc/bitcoin,gjhiggins/vcoincore,vertcoin/vertcoin,bitcoin/bitcoin,vertcoin/vertcoin,rawodb/bitcoin,kallewoof/bitcoin,vertcoin/vertcoin,Sjors/bitcoin,jlopp/statoshi,ahmedbodi/vertcoin,ryanofsky/bitcoin,1185/starwels,mruddy/bitcoin,mruddy/bitcoin,DigitalPandacoin/pandacoin,monacoinproject/monacoin,ericshawlinux/bitcoin,h4x3rotab/BTCGPU,starwels/starwels,paveljanik/bitcoin,sstone/bitcoin,namecoin/namecore,MeshCollider/bitcoin,Kogser/bitcoin,mitchellcash/bitcoin,BTCGPU/BTCGPU,randy-waterhouse/bitcoin,monacoinproject/monacoin,starwels/starwels,mb300sd/bitcoin,ajtowns/bitcoin,MarcoFalke/bitcoin,EthanHeilman/bitcoin,jlopp/statoshi,gjhiggins/vcoincore,jmcorgan/bitcoin,Xekyo/bitcoin,jtimon/bitcoin,untrustbank/litecoin,ElementsProject/elements,instagibbs/bitcoin,Sjors/bitcoin,practicalswift/bitcoin,lbryio/lbrycrd,stamhe/bitcoin,ElementsProject/elements,EthanHeilman/bitcoin,instagibbs/bitcoin,fujicoin/fujicoin,afk11/bitcoin,guncoin/guncoin,jlopp/statoshi,MarcoFalke/bitcoin,andreaskern/bitcoin,untrustbank/litecoin,deeponion/deeponion,bitcoin/bitcoin,globaltoken/globaltoken,fanquake/bitcoin,wellenreiter01/Feathercoin,cryptoprojects/ultimateonlinecash,guncoin/guncoin,deeponion/deeponion,jamesob/bitcoin,peercoin/peercoin,cdecker/bitcoin,ericshawlinux/bitcoin,DigitalPandacoin/pandacoin,lbryio/lbrycrd,fanquake/bitcoin,tecnovert/particl-core,Flowdalic/bitcoin,JeremyRubin/bitcoin,deeponion/deeponion,monacoinproject/monacoin,cdecker/bitcoin,kazcw/bitcoin,mm-s/bitcoin,untrustbank/litecoin,domob1812/huntercore,guncoin/guncoin,MazaCoin/maza,jmcorgan/bitcoin,h4x3rotab/BTCGPU,lateminer/bitcoin,jambolo/bitcoin,afk11/bitcoin,paveljanik/bitcoin,thrasher-/litecoin,guncoin/guncoin,brandonrobertz/namecoin-core,r8921039/bitcoin,lateminer/bitcoin,digibyte/digibyte,h4x3rotab/BTCGPU,GlobalBoost/GlobalBoost,BTCGPU/BTCGPU,midnightmagic/bitcoin,achow101/bitcoin,stamhe/bitcoin,sebrandon1/bitcoin,anditto/bitcoin,sstone/bitcoin,1185/starwels,domob1812/namecore,untrustbank/litecoin,BTCGPU/BTCGPU,Rav3nPL/bitcoin,globaltoken/globaltoken,Rav3nPL/bitcoin,globaltoken/globaltoken,CryptArc/bitcoin,achow101/bitcoin,yenliangl/bitcoin,AkioNak/bitcoin,jtimon/bitcoin,instagibbs/bitcoin,fanquake/bitcoin,thrasher-/litecoin,starwels/starwels,monacoinproject/monacoin,jmcorgan/bitcoin,stamhe/bitcoin,bespike/litecoin,bitcoin/bitcoin,practicalswift/bitcoin,midnightmagic/bitcoin,deeponion/deeponion,midnightmagic/bitcoin,bespike/litecoin,Rav3nPL/bitcoin,Kogser/bitcoin,jonasschnelli/bitcoin,jonasschnelli/bitcoin,bitcoinsSG/bitcoin,DigitalPandacoin/pandacoin,kallewoof/bitcoin,lbryio/lbrycrd,ericshawlinux/bitcoin,Flowdalic/bitcoin,rnicoll/dogecoin,MazaCoin/maza,nikkitan/bitcoin,jmcorgan/bitcoin,bitcoinknots/bitcoin,OmniLayer/omnicore,MarcoFalke/bitcoin,domob1812/namecore,pataquets/namecoin-core,bitcoinsSG/bitcoin,viacoin/viacoin,Kogser/bitcoin,thrasher-/litecoin,thrasher-/litecoin,dscotese/bitcoin,litecoin-project/litecoin,alecalve/bitcoin,pstratem/bitcoin,monacoinproject/monacoin,pataquets/namecoin-core,wellenreiter01/Feathercoin,nikkitan/bitcoin,GroestlCoin/bitcoin,TheBlueMatt/bitcoin,Rav3nPL/bitcoin,GlobalBoost/GlobalBoost,mitchellcash/bitcoin,RHavar/bitcoin,kazcw/bitcoin,peercoin/peercoin,kazcw/bitcoin,joshrabinowitz/bitcoin,FeatherCoin/Feathercoin,pstratem/bitcoin,FeatherCoin/Feathercoin,maaku/bitcoin,jtimon/bitcoin,EthanHeilman/bitcoin,myriadcoin/myriadcoin,CryptArc/bitcoin,JeremyRubin/bitcoin,achow101/bitcoin,jambolo/bitcoin,afk11/bitcoin,r8921039/bitcoin,droark/bitcoin,mm-s/bitcoin,alecalve/bitcoin,achow101/bitcoin,litecoin-project/litecoin,GroestlCoin/GroestlCoin,n1bor/bitcoin,qtumproject/qtum,droark/bitcoin,dscotese/bitcoin,TheBlueMatt/bitcoin,peercoin/peercoin,qtumproject/qtum,GlobalBoost/GlobalBoost,achow101/bitcoin,nikkitan/bitcoin,Sjors/bitcoin,Xekyo/bitcoin,cryptoprojects/ultimateonlinecash,jonasschnelli/bitcoin,particl/particl-core,lateminer/bitcoin,pstratem/bitcoin,MazaCoin/maza,litecoin-project/litecoin,ahmedbodi/vertcoin,instagibbs/bitcoin,cdecker/bitcoin,EthanHeilman/bitcoin,OmniLayer/omnicore,Kogser/bitcoin,wellenreiter01/Feathercoin,particl/particl-core,r8921039/bitcoin,gjhiggins/vcoincore,pataquets/namecoin-core,JeremyRubin/bitcoin,prusnak/bitcoin,donaloconnor/bitcoin,kallewoof/bitcoin,FeatherCoin/Feathercoin,viacoin/viacoin,sipsorcery/bitcoin,namecoin/namecoin-core,midnightmagic/bitcoin,joshrabinowitz/bitcoin,bitcoinknots/bitcoin,jambolo/bitcoin,yenliangl/bitcoin,sebrandon1/bitcoin,dscotese/bitcoin,dscotese/bitcoin,vmp32k/litecoin,digibyte/digibyte,GroestlCoin/GroestlCoin,wellenreiter01/Feathercoin,rnicoll/bitcoin,achow101/bitcoin,Flowdalic/bitcoin,tjps/bitcoin,rawodb/bitcoin,viacoin/viacoin,JeremyRubin/bitcoin,domob1812/huntercore,jmcorgan/bitcoin,deeponion/deeponion,rnicoll/dogecoin,ahmedbodi/vertcoin,tjps/bitcoin,anditto/bitcoin,namecoin/namecore,pataquets/namecoin-core,mb300sd/bitcoin,ElementsProject/elements,maaku/bitcoin,practicalswift/bitcoin,sstone/bitcoin,lbryio/lbrycrd,EthanHeilman/bitcoin,paveljanik/bitcoin,rnicoll/bitcoin,cryptoprojects/ultimateonlinecash,jnewbery/bitcoin,bitcoin/bitcoin,GroestlCoin/bitcoin,afk11/bitcoin,GlobalBoost/GlobalBoost,bespike/litecoin,namecoin/namecoin-core,vmp32k/litecoin,brandonrobertz/namecoin-core,prusnak/bitcoin,bespike/litecoin,wellenreiter01/Feathercoin,n1bor/bitcoin,Kogser/bitcoin,sipsorcery/bitcoin,rawodb/bitcoin,n1bor/bitcoin,MazaCoin/maza,BTCGPU/BTCGPU,ryanofsky/bitcoin,domob1812/bitcoin,brandonrobertz/namecoin-core,lateminer/bitcoin,myriadcoin/myriadcoin,sipsorcery/bitcoin,vmp32k/litecoin,tjps/bitcoin