How to set the output path for building?

I'm working on creating a basic pyoxidizer plugin for Pants (https://github.com/sureshjoshi/pants-pyoxidizer-plugin/) - and it's starting to work, however I cannot get the final binary to a useful directory, and then it's evicted from my Mac.

I'm investigating, but I believe Pants uses some tmp process-execution directories, which are immediately deleted. PyOxidizer appears to only build to relative locations. e.g.

`/private/var/folders/18/q1r7phps28nc9rx5j_0t3jmm0000gp/T/process-executiongGTfnJ/./build/x86_64-apple-darwin/debug/exe/helloworld-bin`

Is there any way to set the binary's output path to an absolute location?

I tried the `OUT_DIR` environment variable, but setting that before calling PyOxidizer doesn't appear to do anything.

Start by tracing how PyOxidizer handles relative build destinations and whether the OUT_DIR environment variable is read. Compare that behavior with Pants's temporary process-execution directory, and verify the result by building the example and confirming the binary is written to an absolute location that survives cleanup.

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