Normalize builds by forcing deterministic behaviour in GraphVizualizer.

Normalize builds by forcing deterministic behaviour in GraphVizualizer. The same graph should result in the same .dot file.

This is not THAT important an issue for most places, but since Google's build system rather aggressively caches build results, having non-deterministic builds really screws up the cache hits.  Also, it's nice to have the diagram not shift each maven run, though the diagram is equivalent. 

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Manually synced
MANUAL_CL=50290086