Make interpolator file path buffer bigger

[menzel-gfdl]

Description Makes an interpolator buffer bigger so that file paths that are > 64 and <=128 characters will work.

Fixes #1467

How Has This Been Tested? I have been using this buffer size in another branch and it hasn't caused any issues.

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] Any dependent changes have been merged and published in downstream modules
• [x] New check tests, if applicable, are included
• [x] make distcheck passes

[thomas-robinson]

@menzel-gfdl can you check the boxes please on this PR.

[menzel-gfdl]

@thomas-robinson Done!