#5357-v110: add OGR_G_SetPointCount + OGR_G_SetPoints to API C (v1.10)

New functions:

void CPL_DLL OGR_G_SetPointCount( OGRGeometryH hGeom, int nNewPointCount );
void CPL_DLL OGR_G_SetPoints( OGRGeometryH hGeom, ... );

Now, QGIS simplifies the geometries fetched from provider, but in OGR-provider we can not use a pre-simplification of the OgrGeometry because GDAL API C has not published one of these functions.