qt: Use "fusion" style on macOS Big Sur with old Qt
qt: Use "fusion" style on macOS Big Sur with old Qt

The "macintosh" style is broken on macOS Big Sur at least for Qt 5.9.8.

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