remove block_header_database from Makefile.am (obsolete file)
remove block_header_database from Makefile.am (obsolete file)

libtetcoin/libtetcoin-blockchain,libmetrocoin/libmetrocoin-blockchain,libtetcoin/libtetcoin-blockchain,libtetcoin/libtetcoin-blockchain,libmetrocoin/libmetrocoin-blockchain,bitprim/bitprim-blockchain-replier,bitprim/bitprim-blockchain-replier,libmetrocoin/libmetrocoin-blockchain