[GRASS5] raster filename length problem

[Hamish]

> > More generally, it would help if we had standardised NAME_MAX and
> > MAPSET_MAX constants, rather than having arbitrary integer literals
> > scattered all over the code.
> 
> I'll try whenever I come across NAME/MAPSET definitions to set them
> to NAME_MAX,MAPSET_MAX. Before adding those to gis.h, how long?
> Is 100 ok during the migration to NAME_MAX,MAPSET_MAX? I'm not
> sure how to capture string overflows.