2024-06-21

daemon: Mark buck-out as a cache dir

Summary:
First see https://github.com/facebook/buck2/issues/650 for the original request

This seems like a pretty reasonable ask. The linked standard is respected by at least tar (https://www.man7.org/linux/man-pages/man1/tar.1.html , search for "cache"), which probably means that it's legit enough that buck2 should participate. In any case, this has very little cost

Reviewed By: stepancheg

Differential Revision: D58797288

fbshipit-source-id: 890fdc0a63863924d5809c1592a4c76c0f202f10