Fix cppcheck warnings

libcdi

scripts/cppcheck.sh

src/Diff.cc

src/Ensstat.cc

src/Exprf.cc

src/Info.cc

src/Output.cc

src/Select.cc

src/Setpartab.cc

src/cdo_cdi_wrapper.cc

src/cdo_history.cc

src/cdo_timer.h

src/cdo_varlist.cc

src/cdo_varlist.h

src/expr.h

src/factory.h

src/knndata.h

src/pointsearch_reg2d.h

src/remap_bicubic.cc

src/remap_conserv.cc