OpenDelta: SV translations

Change-Id: Iaf9940c028980fd517c283d66031ac922b815003
Pass in the source buffer size depend on the input file size

the xdelta might produce huge output if the difference is bigger than
32MB, half of the default buffer size 64MB.[1]

xdelta author suggested nearest power of 2. [2]

[1] http://code.google.com/p/xdelta/wiki/TuningMemoryBudget#Source_buffer_size
[2] http://code.google.com/p/xdelta/issues/detail?id=175

Change-Id: Id4f277373d088986fc314c386b269d0bddfcdd07