ike-sa-manager: Signal entries that we don't actually check out

ike-sa-manager: Signal entries that we don't actually check out

In some cases we call wait_for_entry() but don't actually check out the
entry afterwards (e.g. because it doesn't match certain criteria).  So
there won't be a call to checkin() for such entries causing waiting
threads to get signaled.  Instead, such threads would be blocked until
another thread properly checks out/in the entry (or does a blocking
enumeration).