Fixes #1360. Fix NAG build bug

[mathomp4]

Description

Fixes a build bug with NAG. More of a workaround than a fix I suppose, but it might take @weiyuan-jiang level knowledge to make a reproducer for NAG.

So for now, we implement a fix from @tclune

Related Issue

Closes #1360

Motivation and Context

Lets MAPL build with NAG 7.1

How Has This Been Tested?

Built the branch with Intel, GNU, and NAG. All worked.

I'll also build and run with GEOSgcm, but it seems trivial for that (as it only really affects base/cub2latlon_regridder.F90. But I'll also tag @bena-nasa on this so he can make sure it's good by him.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Trivial change (affects only documentation or cleanup)

Checklist:

• I have tested this change with a run of GEOSgcm (if non-trivial)
• I have added one of the required labels (0 diff, 0 diff trivial, 0 diff structural, non 0-diff)
• I have updated the CHANGELOG.md accordingly following the style of Keep a Changelog

[mathomp4]

This is zero-diff as expected.