Fix some CheckLevelDEEP assertions:
1. In GlobalsPrepareToDestroy, set arenaGlobals->defaultChain to NULL before calling ChainDestroy, to avoid a failed ChainCheck inside ControlFree.
2. In GlobalsPrepareToDestroy, set arenaGlobals->lock to NULL after destroying it, to avoid a failed LockCheck inside ControlFree.
3. In TraceIdMessagesCreate, set tsMessage[ti] and tMessage[ti] together to avoid a failed TraceIdMessagesCheck inside traceMessageInit.
4. In TracePostStartMessage, set tsMessage[ti] to NULL before calling MessagePost, to avoid a failed TraceStartMessageCheck inside ControlFree.
5. Ditto for TracePostMessage and tMessage[ti].