FOREX-Dollar supported before jobs data, Aussie slides after RBA comments

* Dollar index holds above recent 8-week low * Solid U.S. private-sector hiring lifts hope for nonfarm payrolls * Aussie dollar falls after RBA's Stevens warns on currency strength (Adds comments, updates prices) SYDNEY/SINGAPORE, July 3 (Reuters) - The dollar held firm above a recent eight-week low on Thursday, supported by hopes for a healthy rise in nonfarm payrolls, while the Aussie fell ...