adb: add fdevent callback that passes the fdevent.

This is useful for when we don't want to actually store the fdevent
into a separate struct to be able to destroy it, but instead want to
destroy it immediately from the callback.

Test: adb_test
Change-Id: Ief3dbf8ea6a6bd72dc7e73f9ab9b7429e48fc181
3 files changed