[llvm] [CAS] Add OnDiskGraphDB and OnDiskKeyValueDB (PR #114102)

[Steven Wu via llvm-commits]

cachemeifyoucan wrote:

> The fact that it does not occur on RHEL8 or RHEL9 and occurs only on RHEL10 makes it extremely weird.

That is weird. I have trouble to get a RHEL10 container to build llvm. The error looks like some difference in file system memory mapping but it is hard to say without reproducing it. Let me know what you want to do in the next step. This is unit-test so we can disable that for now if we have a good macro to guard it against. 

https://github.com/llvm/llvm-project/pull/114102