Fix seg fault when fd_order is on

[haochey]

Description

The buffer_size is not initialized for all the variable bound constant (e.g. idwbuff(2)%beg:idwbuff(2)%end from PR# 653) when fd_order is on. This will cause seg fault issue on variables like flux_gsrc_n. Maybe @henryleberre can confirm this.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Scope

• This PR comprises a set of related changes with a common goal

If you cannot check the above box, please split your PR into multiple PRs that each have a common goal.

How Has This Been Tested?

Turn on fd_order and the seg fault issue is resolved.

Test Configuration:

• What computers and compilers did you use to test this: MacOS CPU/GCC, Phoenix CPU/GCC, and Delta A100/NVHPC

Checklist

• New and existing tests pass locally with my changes, including with GPU capability enabled (both NVIDIA hardware with NVHPC compilers and AMD hardware with CRAY compilers) and disabled
• This PR does not introduce any repeated code (it follows the DRY principle)
• I cannot think of a way to condense this code and reduce any introduced additional line count

If your code changes any code source files (anything in src/simulation)

To make sure the code is performing as expected on GPU devices, I have:

• Checked that the code compiles using NVHPC compilers
• Ran the code on either V100, A100, or H100 GPUs and ensured the new feature performed as expected (the GPU results match the CPU results)

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

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Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
src/simulation/m_global_parameters.fpp	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

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  Hits              ?     6914           
  Misses            ?     8157           
  Partials          ?      990           

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[sbryngelson]

I'm not sure. Something about this is still confusing to me. Maybe it's clearer to @henryleberre since he just edited all of these.

[sbryngelson]

I think I understand better now after looking at this more properly.