Removed unnecessary synchronization.

Under very high load our application was slowed down 63% with logger p6spy set to info.  This bottleneck went away when we removed p6spy instrumentation.  We run p6spy all the time in prod

I removed the synchronized keyword from P6LogQuery.doLog and made sure that access to the date format was thread safe.  When I did this performance went back to nearly the same as with no p6spy.