Fix #348, Moves interface definition files to inc

Checklist (Please check before submitting)

[x] I reviewed the Contributing Guide.
[x] I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution A clear and concise description of what the contribution is.

Testing performed make install lcov

Expected behavior changes No impact to behavior

System(s) tested on

Additional context Recommend fix of broken workflows as of https://github.com/nasa/CF/commit/b9a88983e7396ce0ae0e42abe82e1fc9fd86bd51 before considering this pull request.

Third party code If included, identify any third party code and provide text file of license

Contributor Info - All information REQUIRED for consideration of pull request -Justin Figueroa, Vantage

nasa / CF