Fix an indexing error in the SOD halo finder

Two lines needed to be changed: I found one, then Nick found the other... teamwork :)
Fix an indexing error in the SOD halo finder

Two lines needed to be changed: I found one, then Nick found the other... teamwork :)

From: Hal Finkel <hfinkel@anl.gov>

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1781 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
Merge branch 'svn/trunk'