Fixed a compiler error on MSVC 2010
Fixed a compiler error on MSVC 2010

Change-Id: I68dea1bf3778a310f6ac59c58830ebce023fb65d

ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,wadejong/avogadrolibs,OpenChemistry/avogadrolibs,ghutchis/avogadrolibs,wadejong/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,wadejong/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,ghutchis/avogadrolibs,wadejong/avogadrolibs