add description of option -v to ncmpigen man page

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1580 c368ceb8-fd28-0410-a457-e46ee1d7cd4a
avoid -Wall compile warnings

git-svn-id: https://svn.mcs.anl.gov/repos/parallel-netcdf/trunk@1581 c368ceb8-fd28-0410-a457-e46ee1d7cd4a