[llvm] [llvm-exegesis] Use hex values when parsing memory mappings (PR #72620)

[Clement Courbet via llvm-commits]

legrosbuffle wrote:

As far as I'd like introducing name churn I don't think we can rely on people reading the release notes for this. We can't know whether someone is relying on these values; doing things properly is probably less work than people debugging the issue on their side.

The 0x opetion avoids changing the name and actually makes it clear that the value is hex.

https://github.com/llvm/llvm-project/pull/72620