[conformal/btcd] cc2c48: Replace map[a]bool with map[a]struct{}

[Tomás Senart]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcd
  Commit: cc2c486791261ff9f95a38c1c33f6edeee81f79c
      
https://github.com/conformal/btcd/commit/cc2c486791261ff9f95a38c1c33f6edeee81f79c
  Author: Tomás Senart <tsen...@gmail.com>
  Date:   2014-07-02 (Wed, 02 Jul 2014)

  Changed paths:
    M blockmanager.go
    M config.go
    M peer.go
    M rpcserver.go
    M rpcwebsocket.go

  Log Message:
  -----------
  Replace map[a]bool with map[a]struct{}

The later uses no memory storage for values and provides the same
functionality.


  Commit: f439dece37c8b4383c4433bc61cc2618a7af373b
      
https://github.com/conformal/btcd/commit/f439dece37c8b4383c4433bc61cc2618a7af373b
  Author: Tomás Senart <tsen...@gmail.com>
  Date:   2014-07-02 (Wed, 02 Jul 2014)

  Changed paths:
    M addrmanager.go
    M blockmanager.go
    M btcd.go
    M peer.go
    M rpcwebsocket.go
    M server.go
    M signal.go
    M util/addblock/import.go

  Log Message:
  -----------
  Use chan struct{} for semaphores

With semaphores we don't actually care about the value passed in. It
makes sense to use a 0 bytes type in these cases.
There is also the added benefit of compiler optimisations for this
specific use case as described here:
https://docs.google.com/document/d/1yIAYmbvL3JxOKOjuCyon7JhW4cSv1wy5hC0ApeGMV9s/pub


Compare: https://github.com/conformal/btcd/compare/76d258e2a15c...f439dece37c8