[Trivial] Fix type used for array init

[pgrete]

PR Summary

Clang just warned me about this. Apparently this was introduced because of clang (2fcd219).
Let's see what CI says (haven't tested locally)

PR Checklist

• Code passes cpplint
• New features are documented.
• Adds a test for any bugs fixed. Adds tests for new features.
• Code is formatted
• Changes are summarized in CHANGELOG.md
• Change is breaking (API, behavior, ...)
  • Change is additionally added to CHANGELOG.md in the breaking section
  • PR is marked as breaking
  • Short summary API changes at the top of the PR (plus optionally with an automated update/fix script)
• CI has been triggered on Darwin for performance regression tests.
• Docs build
• (@lanl.gov employees) Update copyright on changed files

[Yurlungur]

Good catch. Surprised we didn't see that before...

[pgrete]

/Users/runner/work/parthenon/parthenon/src/outputs/restart_hdf5.cpp:217:17: error: constexpr variable 'VNDIM' must be initialized by a constant expression
  constexpr int VNDIM = info.VNDIM;
                ^       ~~~~~~~~~~
/Users/runner/work/parthenon/parthenon/src/outputs/restart_hdf5.cpp:217:25: note: function parameter 'info' with unknown value cannot be used in a constant expression
  constexpr int VNDIM = info.VNDIM;
                        ^
/Users/runner/work/parthenon/parthenon/src/outputs/restart_hdf5.cpp:209:64: note: declared here
                                   const OutputUtils::VarInfo &info,
                                                               ^

I guess that's why the constexpr was removed in first place. Given the danger of a rabbit whole I won't be able to look at this before leaving. Will look at this again in two weeks unless someone else figures out a quick fix.

[Yurlungur]

Pretty sure the following will work:

constexpr int VNDIM = OutputUtils::VarInfo::VNDIM;

will try it and push.

[lroberts36]

LGTM

[lroberts36]

Isn't the extra const here redundant given that it is already constexpr?