XMLParser: drop unused libm dependency

[jainoshika]

This PR removes an unused direct dependency on libm from libXMLParser.

The unused dependency was identified via ldd -u on the official ROOT 6.38.00 binary build for AlmaLinux 9.7.

Checklist:

• tested changes locally

This PR fixes #20731

[guitargeek]

Thank you very much! Just try to keep unrelated changes out of the commit please

[jainoshika]

Fixed — thanks for catching that. I’ve amended the commit. I can follow up with separate PRs for other libraries if you think that would be useful, keeping each change focused.

[github-actions]

Test Results

    22 files      22 suites   3d 19h 25m 21s ⏱️
 3 792 tests  3 792 ✅ 0 💤 0 ❌
80 337 runs  80 337 ✅ 0 💤 0 ❌

Results for commit 6afd261.

[guitargeek]

Thanks!

[guitargeek]

Wait that can't be right. Core is a public dependency of XMLParser, because "TObject.h" is included in the public TXMLAttr.h. So the Core dependency needs to be public.

[jainoshika]

Thanks for the review and explanation. I will close this PR.
For the remaining cases in this issue, are there specific libraries you’d recommend I focus on first - ones that are safe to clean up?
I’m happy to follow your preference.