ImageOverlapSet.h: 2011-03-29 Steven Lambright - Added some safety around...

ImageOverlapSet.h: 2011-03-29 Steven Lambright - Added some safety around p_lonLatOverlaps to (hopefully) get rid of a race condition. 

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2134 41f8697f-d340-4b68-9986-7bafba869bb8