Instead of directly freeing an event source upon removal put it in a
queue later handled by the event loop; either after a dispatch or upon
event loop destruction.
This is necessary to avoid already queued up event sources to be freed
during some other dispatch callback, causing segmentation faults when
the event loop later tries to handle an event from the freed source.
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
When the last idle handler queues another idle handler, we fail to
dispatch that last handler. The wl_list_for_each_safe loop looks up
the next pointer before running the handler, and at that point it points
to the head of the list and the loop terminates.
Instead, just loop until the list is empty.
