JOHANNESBURG/LONDON (Reuters) – GlaxoSmithKline advanced its clear-out of non-core drugs on Wednesday with a deal to sell 25 older brands marketed in Australia to South Africa's Aspen Pharmacare for 172 million pounds. Andrew Witty, chief executive of Britain's biggest drugmaker, said last month during quarterly results that he was looking for further ways to simplify the GSK business, following previous divestments in consumer health. The old Australian brands being bought by Aspen include herpes treatment Valtrex, epilepsy drug Lamictal and the antibiotic Amoxil. …