Updates for FORD Testing

[mathomp4]

Description

Testing with the FORD Documentation maker found a few changes needed to support FORD. These included adding a program statement to the top of a few programs (that only had an end), removing pfio/pfio_io_demo.F90 (see #1567) and fixing a macro redefinition.

Related Issue

Closes #1567

Motivation and Context

Let's me try out FORD with MAPL!

How Has This Been Tested?

I don't see how any of these changes should break the model. Pretty trivial

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]

Re-requesting @tclune review. Apparently I pushed after the review (I removed that pf test that wasn't being run)