Fixed bug causing jigsaw to fail with a singular definite matrix on radar...

Fixed bug causing jigsaw to fail with a singular definite matrix on radar data.  This update fixes issue #1582.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@5101 41f8697f-d340-4b68-9986-7bafba869bb8