blockchain: Correct serialized coinbase height error message.
blockchain: Correct serialized coinbase height error message.

cqswxj2013/btcd,jrick/btcd,hectorj/btcd,jrick/btcd,tb00/btcd,jrick/btcd,BitGo/prova,soapboxsys/ombfullnode,wallclockbuilder/btcd,adiabat/btcd,dajohi/btcd,dajohi/btcd,ltcsuite/ltcd,jongillham/btcd,cqswxj2013/btcd,dan-da/btcd,tb00/btcd,Stash-Crypto/btcd,Roasbeef/btcd,Stash-Crypto/btcd,davecgh/btcd,BitGo/prova,jcmincke/dcrd,jcmincke/dcrd,aakselrod/btcd,aakselrod/btcd,dan-da/btcd,ppcsuite/ppcd,decred/dcrd,jongillham/btcd,decred/dcrd,jrick/dcrd,btcsuite/btcd,ltcsuite/ltcd,dajohi/btcd,stevenroose/btcd,wallclockbuilder/btcd,Roasbeef/btcd,davecgh/btcd,ppcsuite/ppcd,adiabat/btcd,stevenroose/btcd,btcsuite/btcd,soapboxsys/ombfullnode,jcmincke/dcrd,jrick/dcrd,hectorj/btcd