Observer -> clearApc() added function check for 'apc_clear_cache'

Observer -> clearApc() added function check for 'apc_clear_cache'

This is needed because events 'controller_action_postdispatch_adminhtml_cache_flushAll' and 'controller_action_postdispatch_adminhtml_cache_flushSystem' have no check for this unlike the 'Flush APC Cache' Button