fix: Remove illegitimate use of fpos_t
fix: Remove illegitimate use of fpos_t

This causes compiler failure on platforms where fpos_t is not an alias
for int.  We should not be relying the specific implementation of fpos_t

TODO: Verify that saving a specific frame range still works

frizaro/Veloview,Kitware/VeloView,Kitware/VeloView,Kitware/VeloView,frizaro/Veloview,frizaro/Veloview,Kitware/VeloView,Kitware/VeloView,frizaro/Veloview