[conformal/btcchain] 162699: Avoid copying block headers in convenience locals.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcchain
  Commit: 1626994433f20b65d6f8da7603a0f70ffb15c2aa
      
https://github.com/conformal/btcchain/commit/1626994433f20b65d6f8da7603a0f70ffb15c2aa
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-01-19 (Sun, 19 Jan 2014)

  Changed paths:
    M accept.go
    M process.go
    M validate.go

  Log Message:
  -----------
  Avoid copying block headers in convenience locals.

This commit modifies local variables that are used for more convenient
access to a block's header to use pointers.  This avoids copying the
header multiple times.