util: epoll_run: fix event processing loop

The number of pending events returned by epoll_wait is overridden by the
first call to an event handler. Using an additional local variable resolves
this issue.

travis-ci: success for lazy-pages: add non-#PF events handling
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>