[llvm] [memprof] Add access checks to PortableMemInfoBlock::get* (PR #90121)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> Can you also extend the new unit tests to check that the expected bits were set?

I just added a unit test.  Please take a look.  Thanks!

https://github.com/llvm/llvm-project/pull/90121