appender.cxx: Take lock before notifying conditional variable. Use memory_order_acq_rel.
appender.cxx: Take lock before notifying conditional variable. Use
memory_order_acq_rel.

ccpaging/log4cplus,csuideal/log4cplus,csuideal/log4cplus,csuideal/log4cplus,ccpaging/log4cplus,ccpaging/log4cplus,csuideal/log4cplus,ccpaging/log4cplus