Change year, month, day to yr, mo, dy in time_interp

[mlee03]

Description
In this PR, the local subroutine variables year, month, and day in time_interp have been changed to yr, mo, and dy to avoid conflicts with the module level variables YEAR, MONTH, and DAY

Fixes #1052

How Has This Been Tested?
FMS compiles with Intel on the AMD box

Checklist:

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