gl2ps: add version check for USE_SYSTEM_GL2PS
We require changes merged to gl2ps after version 1.3.9. Thus 1.4.0 is a guess for the next version... Anyway, this should disable using the system version for bad versions that VTK doesn't support.
We require changes merged to gl2ps after version 1.3.9. Thus 1.4.0 is a guess for the next version... Anyway, this should disable using the system version for bad versions that VTK doesn't support.