build: call AC_PATH_TOOL for dsymutil in macOS cross-compile
build: call AC_PATH_TOOL for dsymutil in macOS cross-compile

While testing #19530 I noticed that we couldn't call dsymutil after LTO:
```bash
../libtool: line 10643: x86_64-apple-darwin16-dsymutil: command not found
```

This updates configure to call `AC_PATH_TOOL` so that we end up with the
full path to dsymutil, similar to `otool` and `install_name_tool`, ie:
`/bitcoin/depends/x86_64-apple-darwin16/share/../native/bin/x86_64-apple-darwin16-otool`.

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