Fix a bug where streams would linger forever when we had no dirinfo

fixes bug 8387; fix on 0.1.1.11-alpha (code), or on 0.2.4.10-alpha (behavior).
Merge remote-tracking branch 'public/bug8387_024' into maint-0.2.5
Add another 8387 diagnostic

When we run into bug 8387 (if we run into it again), report when we
last called circuit_expire_old_circuits_clientside().  This will let
us know -- if my fix for 8387 doesn't work -- whether my diagnosis
was at least correct.

Suggested by Andrea.