Investigate if macOS logic for parsing '/usr/bin/vmmap' output

[Eilon]

See this comment thread from an earlier PR: https://github.com/dotnet/coreclr/pull/20402/files#r227586471

There's code in src/pal/src/thread/process.cpp that parses the output of a command line tool on macOS to detect certain metadata of an app, and it includes logic to skip over unwanted parts of metadata.

In the PR a concern was raised that the portion that tries to skip over the VSIZE RSDNT DIRTY SWAP metadata columns might have a limitation:

From @Eilon
Out of curiosity, can the VSIZE RSDNT DIRTY SWAP fields never have an M in there for megabytes? Are they always in kilobytes?

So I'm logging this bug so that it can be investigated further:

From @Eilon
Is it possible to create a test case with an app that has a really large "one of those things" to see what it is? E.g. what if an app has more than 99,999KB of VSIZE? (only 5-digit numbers fit in the table)

Is it worth looking into the parsing further? To be clear, I have no background in this at all, just saw something curious.

[Eilon]

Tagging @mikem8361 (I can't assign issues in this repo).

[mikem8361]

The vmmap code has been replaced by the proc_pidinfo API.