util: Define SECCOMP_RET_KILL_PROCESS if not provided by the headers
util: Define SECCOMP_RET_KILL_PROCESS if not provided by the headers

Define `SECCOMP_RET_KILL_PROCESS` as it isn't defined in the headers, as
is the case for the GUIX build on this platform.

jamesob/bitcoin,domob1812/namecore,bitcoinsSG/bitcoin,mm-s/bitcoin,Xekyo/bitcoin,AkioNak/bitcoin,instagibbs/bitcoin,domob1812/bitcoin,fanquake/bitcoin,fujicoin/fujicoin,dscotese/bitcoin,bitcoinsSG/bitcoin,MarcoFalke/bitcoin,mm-s/bitcoin,mruddy/bitcoin,sipsorcery/bitcoin,GroestlCoin/bitcoin,GroestlCoin/bitcoin,AkioNak/bitcoin,jlopp/statoshi,GroestlCoin/bitcoin,fanquake/bitcoin,sipsorcery/bitcoin,andreaskern/bitcoin,namecoin/namecoin-core,namecoin/namecore,namecoin/namecoin-core,bitcoin/bitcoin,particl/particl-core,dscotese/bitcoin,bitcoin/bitcoin,prusnak/bitcoin,jambolo/bitcoin,andreaskern/bitcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,dscotese/bitcoin,MarcoFalke/bitcoin,fanquake/bitcoin,achow101/bitcoin,andreaskern/bitcoin,sstone/bitcoin,bitcoinknots/bitcoin,kallewoof/bitcoin,andreaskern/bitcoin,bitcoinknots/bitcoin,jamesob/bitcoin,GroestlCoin/GroestlCoin,mruddy/bitcoin,bitcoin/bitcoin,Xekyo/bitcoin,andreaskern/bitcoin,jambolo/bitcoin,jlopp/statoshi,namecoin/namecore,lateminer/bitcoin,tecnovert/particl-core,Xekyo/bitcoin,kallewoof/bitcoin,Xekyo/bitcoin,GroestlCoin/GroestlCoin,tecnovert/particl-core,achow101/bitcoin,achow101/bitcoin,domob1812/namecore,jlopp/statoshi,domob1812/namecore,GroestlCoin/GroestlCoin,fujicoin/fujicoin,instagibbs/bitcoin,achow101/bitcoin,kallewoof/bitcoin,jlopp/statoshi,achow101/bitcoin,bitcoinsSG/bitcoin,prusnak/bitcoin,Xekyo/bitcoin,GroestlCoin/GroestlCoin,dscotese/bitcoin,anditto/bitcoin,instagibbs/bitcoin,instagibbs/bitcoin,ajtowns/bitcoin,sstone/bitcoin,namecoin/namecore,prusnak/bitcoin,namecoin/namecoin-core,domob1812/bitcoin,namecoin/namecoin-core,bitcoinsSG/bitcoin,tecnovert/particl-core,mm-s/bitcoin,jlopp/statoshi,pataquets/namecoin-core,prusnak/bitcoin,bitcoinknots/bitcoin,GroestlCoin/GroestlCoin,anditto/bitcoin,lateminer/bitcoin,tecnovert/particl-core,Xekyo/bitcoin,bitcoin/bitcoin,ajtowns/bitcoin,jlopp/statoshi,GroestlCoin/bitcoin,namecoin/namecoin-core,bitcoinsSG/bitcoin,domob1812/bitcoin,lateminer/bitcoin,fanquake/bitcoin,anditto/bitcoin,jamesob/bitcoin,jamesob/bitcoin,lateminer/bitcoin,mruddy/bitcoin,pataquets/namecoin-core,instagibbs/bitcoin,particl/particl-core,AkioNak/bitcoin,anditto/bitcoin,fanquake/bitcoin,domob1812/namecore,domob1812/namecore,domob1812/bitcoin,particl/particl-core,kallewoof/bitcoin,mruddy/bitcoin,kallewoof/bitcoin,jambolo/bitcoin,bitcoin/bitcoin,lateminer/bitcoin,dscotese/bitcoin,sstone/bitcoin,mruddy/bitcoin,prusnak/bitcoin,jambolo/bitcoin,sipsorcery/bitcoin,namecoin/namecore,kallewoof/bitcoin,namecoin/namecore,bitcoin/bitcoin,pataquets/namecoin-core,MarcoFalke/bitcoin,jambolo/bitcoin,sstone/bitcoin,fujicoin/fujicoin,fanquake/bitcoin,MarcoFalke/bitcoin,MarcoFalke/bitcoin,domob1812/bitcoin,ajtowns/bitcoin,namecoin/namecoin-core,jamesob/bitcoin,fujicoin/fujicoin,sstone/bitcoin,bitcoinsSG/bitcoin,mm-s/bitcoin,AkioNak/bitcoin,ajtowns/bitcoin,pataquets/namecoin-core,pataquets/namecoin-core,mm-s/bitcoin,GroestlCoin/bitcoin,pataquets/namecoin-core,fujicoin/fujicoin,bitcoinknots/bitcoin,anditto/bitcoin,tecnovert/particl-core,particl/particl-core,andreaskern/bitcoin,fujicoin/fujicoin,MarcoFalke/bitcoin,instagibbs/bitcoin,mm-s/bitcoin,sstone/bitcoin,bitcoinknots/bitcoin,jamesob/bitcoin,sipsorcery/bitcoin,AkioNak/bitcoin,lateminer/bitcoin,jambolo/bitcoin,particl/particl-core,sipsorcery/bitcoin,particl/particl-core,sipsorcery/bitcoin,ajtowns/bitcoin,prusnak/bitcoin,AkioNak/bitcoin,achow101/bitcoin,ajtowns/bitcoin,domob1812/bitcoin,namecoin/namecore,dscotese/bitcoin,mruddy/bitcoin,tecnovert/particl-core,domob1812/namecore,anditto/bitcoin