SpatialReference::set(): store coordinate epoch from OGRSpatialRefere…

…nce built from SetFromUserInput()

This is useful to get the epoch for a SpatialReference built from a
string like 'urn:ogc:def:coordinateMetadata:AUTHORTIY::CODE code' (since
OSGeo/gdal#8340 and OSGeo/PROJ#3884), which
resolves to a CoordinateMetadata object with a CRS and potentially a
coordinate epoch

pdal/SpatialReference.cpp

@@ -237,6 +237,8 @@ void SpatialReference::set(std::string v)
         throw pdal_error(oss.str());
     }
 
+    m_epoch = srs.GetCoordinateEpoch();
+
     m_wkt = exportToWkt(&srs);
 }