r12141: - move epoll related code into one big #ifdef, and use dummy #define's

r12141: - move epoll related code into one big #ifdef, and use dummy #define's
  for the case where, epoll isn't available at compile time
- only pass the private std_event_context, to the local function,
  to get rid of the talloc_get_type() calls
- use the private pointer to std_event_context_init() to decide if we want to
  disable epoll at runtime

metze
(This used to be commit de322ea8b761df5434e60879b7eae3796ea68007)