[clang] [Serialization] Check for stack exhaustion when reading declarations (PR #79875)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> I think we should apply @ChuanqiXu9 suggestion and merge that without tests. At worse it's harmless, at best it solves an actual issue for users. We have precedent for not being able to test resource exhaustion fixes.

I would not be opposed to landing with a test, but I think such a test would be challenging because stack exhaustion is often slow to trigger and highly machine-dependent (so I can imagine the test failing "randomly" for different configurations or under different workloads, or being a very slow test to execute). So if there's a simple, quick-to-execute, reliably-failing test we can add, then great! But if there's not, I would be fine landing without tests.

https://github.com/llvm/llvm-project/pull/79875