Fix some warnings about testing for unsigned values less than zero.  Most of these were system calls that are defined to succeed always.
Fix some warnings about testing for unsigned values less than zero.  Most of these were system calls that are defined to succeed always.

git-svn-id: 98787b36aaefbae4b30fa755be920954cd25e1e4@1910 ae7d391e-3f74-4a2b-a0db-a8776840fd2a

mn200/polyml,dcjm/polyml,polyml/polyml,polyml/polyml,polyml/polyml,mn200/polyml,mn200/polyml,dcjm/polyml,dcjm/polyml,mn200/polyml,dcjm/polyml,polyml/polyml