Don't link with ROOT's libNew

[hansenjo]

Fixes issue #5. Closes #3 and #4.

This PR supersedes (includes) my earlier PR #3 and PR #4 as well as the trivial fix for the case-sensitive file name clash on macOS that was already merged in the japan repo.

[hansenjo]

Maybe hold off on this until we do some more testing. Here's why: From the discussion at https://root-forum.cern.ch/t/aborting-with-std-align-val-t-is-not-implemented-yet-rhel-9-2/55989, I gather that

• TMapFile requires linking with libNew
• JAPAN instantiates a TMapFile as part of QwRootFile, which is used a lot
• libNew is currently broken (when compiling with -std=c++17? This point isn't completely clear.)
• ROOT 6.30 requires C++17. Hence TMapFile is currently unusable in ROOT 6.30.

This is particularly problematic because

• The latest macOS (14, "Sonoma") requires ROOT 6.30 (at least according to the Release Notes).
• The precompiled packages of ROOT for RHEL/Alma 9 are compiled with -std=c++17.

Hence, JAPAN is currently unusable on macOS Sonoma. It is also unusable on Alma 9 with ROOT from the repositories. As a workaround, one can use a custom-compiled version of ROOT 6.28 or earlier that uses -std=c++14, except on macOS Sonoma.

I need to do more testing to confirm this, i.e. run JAPAN on Alma 9 with several versions of ROOT.

Questions:

• Do we really need TMapFile? I mean, after making the change not to link with libNew, things do seem to work. (We should check if they really do, i.e. compare known-good results from Linux with results obtained with this patch here.)
• Do we want to wait for the ROOT team to fix it? This could take a while, possibly a long while. The thread I referenced is from August 2023, and Philippe Canal suggests to the OP (hear this!) that he implement the missing overload of operator new himself! Not exactly a promising situation.

[hansenjo]

See also the discussion here https://github.com/root-project/root/issues/13511

[hansenjo]

I've modified this PR so that the TMapFile functionality is only disabled if the CXX standard is >= 17, which reflects the current situation with ROOT (any version).

If the standard is >= 17, then

• QwRootFile no longer contains any code that instantiates a TMapFile object;
• if the enable-mapfile option is given, a warning is printed and the option is disabled; and
• ROOT's libNew is removed from the ROOT::Libraries target and so no longer linked.

Once ROOT is patched (who knows when), we can refine the conditionals used for this logic to exclude only affected ROOT versions.

[hansenjo]

Looks like the ROOT team is working on this, albeit slowly: https://github.com/root-project/root/pull/14792. I think we should wait for them to finish the fix, then put a warning in our build system if a problematic combination of ROOT/C++ standard is detected.