CANADA STOCKS-Valeant, gold miners pull TSX to one-week low

* TSX falls 47.06 points, or 0.32 percent, to 14,610.96 * Eight of the 10 main index sectors decline * Valeant drops after raising cash portion of Allergan bid By John Tilak TORONTO, May 28 (Reuters) - Canada's main stock index dropped on Wednesday, weighed down by weakness in Valeant Pharmaceuticals after the drugmaker raised its takeover offer for Allergan Inc and by a slide in gold-mining shares as the bullion price fell. Valeant's stock gave back 2.1 percent after the co