Don't process unrequested, low-work blocks
Don't process unrequested, low-work blocks

A peer could try to waste our resources by sending us unrequested blocks with
low work, eg to fill up our disk.  Since
e2652002b6011f793185d473f87f1730c625593b we no longer request blocks until we
know we're on a chain with more than nMinimumChainWork (our anti-DoS
threshold), but we would still process unrequested blocks that had more work
than our tip.  This commit fixes that behavior.

Github-Pull: #11458
Rebased-From: ce8cd7a7da9174ab151172fc0ce97b5164637cf3

Anfauglith/iop-hd,gjhiggins/vcoincore,qtumproject/qtum,gjhiggins/vcoincore,Anfauglith/iop-hd,GroestlCoin/GroestlCoin,BitzenyCoreDevelopers/bitzeny,tecnovert/particl-core,GroestlCoin/GroestlCoin,gjhiggins/vcoincore,wangxinxi/litecoin,Anfauglith/iop-hd,qtumproject/qtum,romanornr/viacoin,UFOCoins/ufo,particl/particl-core,Jcing95/iop-hd,gjhiggins/vcoincore,GroestlCoin/GroestlCoin,particl/particl-core,wangxinxi/litecoin,romanornr/viacoin,tecnovert/particl-core,BitzenyCoreDevelopers/bitzeny,qtumproject/qtum,BitzenyCoreDevelopers/bitzeny,GroestlCoin/bitcoin,GroestlCoin/GroestlCoin,romanornr/viacoin,particl/particl-core,qtumproject/qtum,UFOCoins/ufo,digibyte/digibyte,particl/particl-core,Jcing95/iop-hd,qtumproject/qtum,Jcing95/iop-hd,GroestlCoin/GroestlCoin,Jcing95/iop-hd,tecnovert/particl-core,romanornr/viacoin,GroestlCoin/bitcoin,Jcing95/iop-hd,qtumproject/qtum,digibyte/digibyte,gjhiggins/vcoincore,BitzenyCoreDevelopers/bitzeny,Anfauglith/iop-hd,particl/particl-core,GroestlCoin/bitcoin,wangxinxi/litecoin,particl/particl-core,digibyte/digibyte,qtumproject/qtum,digibyte/digibyte,UFOCoins/ufo,tecnovert/particl-core,Anfauglith/iop-hd,GroestlCoin/bitcoin,GroestlCoin/bitcoin,GroestlCoin/bitcoin,BitzenyCoreDevelopers/bitzeny,GroestlCoin/GroestlCoin,gjhiggins/vcoincore,digibyte/digibyte,Jcing95/iop-hd,romanornr/viacoin,wangxinxi/litecoin,wangxinxi/litecoin,tecnovert/particl-core,romanornr/viacoin,BitzenyCoreDevelopers/bitzeny,digibyte/digibyte,UFOCoins/ufo,wangxinxi/litecoin,tecnovert/particl-core,Anfauglith/iop-hd,UFOCoins/ufo,UFOCoins/ufo