[conformal/btcwire] 2de1b7: Add a benchmark for TxSha.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcwire
  Commit: 2de1b73d122516c0c194698328e4f3fb7d87382d
      
https://github.com/conformal/btcwire/commit/2de1b73d122516c0c194698328e4f3fb7d87382d
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-03-20 (Thu, 20 Mar 2014)

  Changed paths:
    M bench_test.go

  Log Message:
  -----------
  Add a benchmark for TxSha.

This commit adds a benchmark for the TxSha function of a MsgTx.