Use optimized miner only for amd64. Fixes compilation on i386 (and other archs, if compiling anywhere else at all).
Use optimized miner only for amd64. Fixes compilation on i386 (and other archs, if compiling anywhere else at all).

dlitz/bitcoin-debian,dlitz/bitcoin-debian,dlitz/bitcoin-debian,dlitz/bitcoin-debian,dlitz/bitcoin-debian