(stable) Let "phlog()" log Throwables
Ref T13250. If you "phlog()" a Throwable, it doesn't recognize that it's an exception and sends you down the "unknown type of object" pathway. You get a one-line "Object Error" message in the log.
Instead, treat it more like an Exception and log a message + stack trace.
Test Plan: Logged some Throwables, got sensible information about them.
Reviewed By: amckinley
Maniphest Tasks: T13250
Differential Revision: https://secure.phabricator.com/D20143