[df] Avoid cling pointer check in RNTupleColumnReader

[vepadulano]

Align behaviour to all other RDF column readers.

[github-actions]

Test Results

    22 files      22 suites   3d 14h 35m 34s ⏱️
 3 850 tests  3 849 ✅ 0 💤 1 ❌
76 028 runs  76 027 ✅ 0 💤 1 ❌

For more details on these failures, see this check.

Results for commit 6be19d0.

[hahnjo]

This doesn't really make sense to me because the cxx file is not run through Cling...

[vepadulano]

This doesn't really make sense to me because the cxx file is not run through Cling...

Yes I'm still trying to understand the exact scope and motivation to use R__CLING_PTRCHECK(off), I've discussed this with @vgvassilev a bit as well. This is done for all column readers in RDF. I do agree that the implementation file is already compiled so cling shouldn't be interfering anyway... perhaps the presence of the macro in other column readers is a remnant from the time the column readers were class templates and had to be JITted?

OTOH, there may be other places in RDF where this macro should be added and it's not added yet.