[conformal/btcd] 83cffc: Use chan struct{} for tx/blockProcessed chans.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcd
  Commit: 83cffc5d27479a844133f6b0f6f00d39895a1a4b
      
https://github.com/conformal/btcd/commit/83cffc5d27479a844133f6b0f6f00d39895a1a4b
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-07-10 (Thu, 10 Jul 2014)

  Changed paths:
    M blockmanager.go
    M peer.go

  Log Message:
  -----------
  Use chan struct{} for tx/blockProcessed chans.

These channels are being used as semaphores, so it's more efficient to use
a 0-byte type and allow compiler optimizations for the specific use case.