Summary: Infer cannot tell if a procdesc has changed across procedure runs. If we want procedure-level incrementality, it has to know how to compute this information. This diff implements this capability by comparing a procdesc to an existing one before it is saved to disk, and marking the new one as unchanged if applicable.
Summary:
This commit is the result of
`find infer/src -name '*.ml' -or -name '*.mli' -exec ocp-indent -i \{\} \;`
and
`INFER_CHECK_COPYRIGHT=1 InferPrint`