Dump torch::jit::AliasDb objects as Graphviz files (#50452)
Summary:
This PR adds a simple debugging helper which exports the AliasDb state as a [GraphViz](http://www.graphviz.org/) graph definition. The generated files can be viewed with any Graphviz viewer (including online based, for example http://viz-js.com)
Usage:
1. Call `AliasDb::dumpToGraphvizFile()` from a debugger. Using gdb for example:
`call aliasDb_->dumpToGraphvizFile("alias.dot")`
2. Add explicit calls to `AliasDb::dumpToGraphvizFile()`, which returns `true` if it succeeds.
An example output file is attached: [example.zip](https://github.com/pytorch/pytorch/files/5805840/example.zip)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50452
Reviewed By: ngimel
Differential Revision: D25980222
Pulled By: eellison
fbshipit-source-id: 47805a0a81ce73c6ba859340d37b9a806f9000d5
