The struggle to stay warm as energy bills soar across Europe finally hit the Paris men’s catwalks. The French solution? Let them wear polo necks. At Givenchy they were high and black, while at Wales Bonner, they came in tight salmon pink. Elsewhere, there were classic black rollnecks at Hed Mayner worn with faux fur stoles, and candy pink versions at Walter Van Beirendonck. On the opening night of Paris fashion week, Saint Laurent showed funnel-neck jumpers, some of which morphed into gowns. Covering their wearer’s mouths, they seemed to swallow the models whole. The polo neck has a long tradition within European style. “They’re a classic,” agreed Matthew M.…