[GRASS-dev] r60691 Vect_get_centroid_area(): fix seg fault with no centroid

GRASS GIS GRASS GIS developer
1

The change is r60691 does not make sense. Passing a line id of < 1 is
a programmer error and the respective module calling
Vect_get_centroid_area() needs to be fixed, not the library. Reverted
in r61447.

Markus M