fix memory allignment for 32-bit architectures (#668) (#269)
fix memory allignment for 32-bit architectures (#668) (#269)

having 3 int32s above the uint64s in the struct
will cause misalignment for some 32-bit architectures.
see https://golang.org/pkg/sync/atomic/#pkg-note-BUG
This aligns bytesReceived and bytesSent.
jrick/dcrd,decred/dcrd,jrick/btcd,jcmincke/dcrd,jrick/dcrd,decred/dcrd,jrick/btcd,jcmincke/dcrd,jrick/btcd,jcmincke/dcrd