Police have arrested a mother for leaving her five-year-old son unattended in a public housing flat in northern Hong Kong in the early hours of Tuesday.The young boy approached a security guard at 3.30am in the ground-floor lobby of a public housing block in Po Tin Estate off Ming Kum Road, Tuen Mun, and asked for food.“He told the security guard that he felt hungry,” a police source said.Officers later arrested a 42-year-old woman on suspicion of ill-treatment or neglect of a child.As of 12…