[hist] fix x0 printEntries in THnSparse/THnBase

[ferdymercury]

This Pull request:

Changes or fixes:

Fixes https://its.cern.ch/jira/browse/ROOT-10705

Checklist:

• tested changes locally
• updated the docs (if necessary)

[phsft-bot]

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default
How to customize builds

[github-actions]

Test Results

    12 files      12 suites   2d 2h 57m 28s ⏱️
 2 565 tests  2 565 ✅ 0 💤 0 ❌
29 036 runs  29 036 ✅ 0 💤 0 ❌

Results for commit 49cd6e3.

♻️ This comment has been updated with latest results.

[dpiparo]

Hi @ferdymercury , thanks a lot for this code. Do you think we can also add a test for it in root or roottest?

[ferdymercury]

You are welcome! Yes, sure, here it is: root-project/roottest#1086

[lmoneta]

LGTM !
A small suggestion, I would not use C functions like strchr but a TString and TString::Contains

[ferdymercury]

LGTM ! A small suggestion, I would not use C functions like strchr but a TString and TString::Contains

Thanks!
wrt strchr: It was just for consistency with the rest of the file.
There are 17x uses of strchr and I didn't feel like changing them all in this PR :)