[conformal/btcdb] 1b51d5: In FetchHeightRange, preallocate the hash array.

[David Hill]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcdb
  Commit: 1b51d58e556c384ac657d69b0c8100b942223ce6
      
https://github.com/conformal/btcdb/commit/1b51d58e556c384ac657d69b0c8100b942223ce6
  Author: David Hill <dh...@conformal.com>
  Date:   2014-03-20 (Thu, 20 Mar 2014)

  Changed paths:
    M ldb/block.go
    M ldb/leveldb.go

  Log Message:
  -----------
  In FetchHeightRange, preallocate the hash array.

Change FetchBlockByHeight to do the database lookup itself instead of
calling getBlkByHeight.  This saves an allocation of the entire block,
which it wasn't using.

In OpenDB, use fetchBlockShaByHeight instead of getBlkByHeight since it
only needs the sha.  This saves memory on startup.

ok drahn@