[llvm] Reduce llvm-gsymutil memory usage (PR #91023)

[Kevin Frei via llvm-commits]

kevinfrei wrote:

> Per my understanding, these two mutex are required to protect any read/write to DieArray field? If so, there seem to be many more accesses of this field not protected?

They're there for protected the allocation & population, or destruction of the DieArrays, not generally reading/writeing those fields. There needs to be two (for just the first CUDie, and then the whole array) as populating the entire array can trigger a request to populate just the first.

https://github.com/llvm/llvm-project/pull/91023