[compiler-rt] [scudo] Make guard pages optional in the secondary (PR #125960)

[via llvm-commits]

pirama-arumuga-nainar wrote:

> Pirama, this is relatively small, but if you don't think you have context to properly review it, let me know.

The library changes LGTM.  The new tests seem a bit involved.  I will check with you tomorrow if there are any nuances in the test that I need to pay attention to.

https://github.com/llvm/llvm-project/pull/125960