[trivial] Remove misleading 'const'
[trivial] Remove misleading 'const'

Returning by const value is only meaningful in a specific circumstance around
user defined types. In this case, the const is not enforcing any restrictions
on the call site, so is misleading.

fanquake/bitcoin,fujicoin/fujicoin,litecoin-project/litecoin,MarcoFalke/bitcoin,MeshCollider/bitcoin,domob1812/namecore,andreaskern/bitcoin,kallewoof/bitcoin,litecoin-project/litecoin,cdecker/bitcoin,anditto/bitcoin,anditto/bitcoin,achow101/bitcoin,cdecker/bitcoin,JeremyRubin/bitcoin,ajtowns/bitcoin,bitcoinsSG/bitcoin,domob1812/bitcoin,bitcoin/bitcoin,bitcoin/bitcoin,fanquake/bitcoin,EthanHeilman/bitcoin,dscotese/bitcoin,particl/particl-core,rnicoll/dogecoin,JeremyRubin/bitcoin,jlopp/statoshi,sstone/bitcoin,EthanHeilman/bitcoin,apoelstra/bitcoin,jlopp/statoshi,practicalswift/bitcoin,bitcoinsSG/bitcoin,rnicoll/dogecoin,pstratem/bitcoin,domob1812/bitcoin,fujicoin/fujicoin,alecalve/bitcoin,pataquets/namecoin-core,n1bor/bitcoin,ElementsProject/elements,apoelstra/bitcoin,litecoin-project/litecoin,lateminer/bitcoin,Xekyo/bitcoin,midnightmagic/bitcoin,litecoin-project/litecoin,n1bor/bitcoin,rnicoll/bitcoin,litecoin-project/litecoin,MarcoFalke/bitcoin,mruddy/bitcoin,bitcoinknots/bitcoin,Sjors/bitcoin,AkioNak/bitcoin,namecoin/namecoin-core,midnightmagic/bitcoin,GroestlCoin/GroestlCoin,pataquets/namecoin-core,sipsorcery/bitcoin,cdecker/bitcoin,EthanHeilman/bitcoin,kallewoof/bitcoin,ajtowns/bitcoin,jamesob/bitcoin,mruddy/bitcoin,rnicoll/bitcoin,namecoin/namecoin-core,sstone/bitcoin,alecalve/bitcoin,rnicoll/dogecoin,achow101/bitcoin,GroestlCoin/bitcoin,jlopp/statoshi,jonasschnelli/bitcoin,GroestlCoin/GroestlCoin,alecalve/bitcoin,practicalswift/bitcoin,prusnak/bitcoin,n1bor/bitcoin,pataquets/namecoin-core,fujicoin/fujicoin,GroestlCoin/GroestlCoin,MeshCollider/bitcoin,pataquets/namecoin-core,GroestlCoin/bitcoin,lateminer/bitcoin,achow101/bitcoin,sstone/bitcoin,bitcoinknots/bitcoin,midnightmagic/bitcoin,practicalswift/bitcoin,prusnak/bitcoin,Sjors/bitcoin,GroestlCoin/GroestlCoin,JeremyRubin/bitcoin,apoelstra/bitcoin,ajtowns/bitcoin,anditto/bitcoin,jambolo/bitcoin,particl/particl-core,fanquake/bitcoin,jambolo/bitcoin,ajtowns/bitcoin,jonasschnelli/bitcoin,bitcoin/bitcoin,Xekyo/bitcoin,MarcoFalke/bitcoin,kallewoof/bitcoin,domob1812/bitcoin,domob1812/bitcoin,midnightmagic/bitcoin,pstratem/bitcoin,jambolo/bitcoin,ElementsProject/elements,jambolo/bitcoin,ajtowns/bitcoin,MeshCollider/bitcoin,andreaskern/bitcoin,fanquake/bitcoin,domob1812/namecore,jnewbery/bitcoin,Sjors/bitcoin,fujicoin/fujicoin,EthanHeilman/bitcoin,prusnak/bitcoin,rnicoll/dogecoin,jamesob/bitcoin,namecoin/namecore,bitcoinsSG/bitcoin,jonasschnelli/bitcoin,yenliangl/bitcoin,fujicoin/fujicoin,bitcoinknots/bitcoin,instagibbs/bitcoin,qtumproject/qtum,alecalve/bitcoin,lateminer/bitcoin,Xekyo/bitcoin,particl/particl-core,jonasschnelli/bitcoin,MeshCollider/bitcoin,ElementsProject/elements,cdecker/bitcoin,rnicoll/bitcoin,namecoin/namecoin-core,yenliangl/bitcoin,mm-s/bitcoin,practicalswift/bitcoin,namecoin/namecore,rnicoll/bitcoin,sipsorcery/bitcoin,mruddy/bitcoin,pstratem/bitcoin,mruddy/bitcoin,namecoin/namecore,jnewbery/bitcoin,dscotese/bitcoin,lateminer/bitcoin,jambolo/bitcoin,dscotese/bitcoin,Sjors/bitcoin,bitcoinknots/bitcoin,n1bor/bitcoin,GroestlCoin/GroestlCoin,namecoin/namecoin-core,Xekyo/bitcoin,JeremyRubin/bitcoin,sstone/bitcoin,pstratem/bitcoin,AkioNak/bitcoin,GroestlCoin/bitcoin,tecnovert/particl-core,achow101/bitcoin,tecnovert/particl-core,jlopp/statoshi,jnewbery/bitcoin,prusnak/bitcoin,alecalve/bitcoin,apoelstra/bitcoin,AkioNak/bitcoin,mm-s/bitcoin,GroestlCoin/bitcoin,ElementsProject/elements,prusnak/bitcoin,tecnovert/particl-core,domob1812/namecore,bitcoinsSG/bitcoin,n1bor/bitcoin,kallewoof/bitcoin,jnewbery/bitcoin,Xekyo/bitcoin,sipsorcery/bitcoin,tecnovert/particl-core,bitcoinsSG/bitcoin,yenliangl/bitcoin,namecoin/namecore,qtumproject/qtum,instagibbs/bitcoin,mm-s/bitcoin,qtumproject/qtum,particl/particl-core,bitcoin/bitcoin,litecoin-project/litecoin,ElementsProject/elements,namecoin/namecoin-core,AkioNak/bitcoin,apoelstra/bitcoin,jnewbery/bitcoin,dscotese/bitcoin,sipsorcery/bitcoin,jlopp/statoshi,mm-s/bitcoin,JeremyRubin/bitcoin,tecnovert/particl-core,particl/particl-core,jamesob/bitcoin,instagibbs/bitcoin,pstratem/bitcoin,jambolo/bitcoin,andreaskern/bitcoin,jonasschnelli/bitcoin,lateminer/bitcoin,andreaskern/bitcoin,Sjors/bitcoin,jamesob/bitcoin,EthanHeilman/bitcoin,andreaskern/bitcoin,domob1812/bitcoin,Xekyo/bitcoin,mruddy/bitcoin,bitcoin/bitcoin,namecoin/namecore,yenliangl/bitcoin,mm-s/bitcoin,domob1812/namecore,rnicoll/dogecoin,pstratem/bitcoin,AkioNak/bitcoin,ElementsProject/elements,EthanHeilman/bitcoin,fanquake/bitcoin,sstone/bitcoin,MeshCollider/bitcoin,anditto/bitcoin,domob1812/namecore,achow101/bitcoin,sipsorcery/bitcoin,MarcoFalke/bitcoin,sipsorcery/bitcoin,andreaskern/bitcoin,midnightmagic/bitcoin,jamesob/bitcoin,bitcoinsSG/bitcoin,jamesob/bitcoin,instagibbs/bitcoin,GroestlCoin/bitcoin,instagibbs/bitcoin,GroestlCoin/bitcoin,qtumproject/qtum,mm-s/bitcoin,ajtowns/bitcoin,fujicoin/fujicoin,jlopp/statoshi,fanquake/bitcoin,kallewoof/bitcoin,mruddy/bitcoin,lateminer/bitcoin,dscotese/bitcoin,sstone/bitcoin,rnicoll/bitcoin,MarcoFalke/bitcoin,AkioNak/bitcoin,yenliangl/bitcoin,prusnak/bitcoin,rnicoll/bitcoin,tecnovert/particl-core,domob1812/bitcoin,pataquets/namecoin-core,practicalswift/bitcoin,midnightmagic/bitcoin,apoelstra/bitcoin,qtumproject/qtum,achow101/bitcoin,MarcoFalke/bitcoin,kallewoof/bitcoin,pataquets/namecoin-core,n1bor/bitcoin,instagibbs/bitcoin,anditto/bitcoin,JeremyRubin/bitcoin,yenliangl/bitcoin,dscotese/bitcoin,namecoin/namecoin-core,bitcoinknots/bitcoin,qtumproject/qtum,cdecker/bitcoin,cdecker/bitcoin,GroestlCoin/GroestlCoin,qtumproject/qtum,namecoin/namecore,particl/particl-core,bitcoin/bitcoin,practicalswift/bitcoin,MeshCollider/bitcoin,alecalve/bitcoin,anditto/bitcoin,domob1812/namecore