Show event dispatch in the ServiceProfiler

Summary: This makes scripts much easier to debug with --trace, in particular. Also fix the old 'flock' name (now 'lock').

Test Plan: Ran emit_test_event.php --trace.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1092

Differential Revision: https://secure.phabricator.com/D2918