Bug #22309 FileLogHandler::createNewFile() isn't thread safe - may loose log messages

Description:
00165   m_pLogFile->close();  
00166   if (!File_class::rename(m_pLogFile->getName(), newName))
00167   {     
00168     setErrorCode(errno);
00169     rc = false;
00170   }
00171 
00172   // Open again
00173   if (!m_pLogFile->open())
00174   {
00175     setErrorCode(errno);
00176     rc = false;
00177   }             

Writes to log could come in between close and open

How to repeat:
be unlucky.

Suggested fix:
lock somehow.

Initially, freopen() looked like a possibility.

But, it seems that on some FreeBSD systems, freopen() hasn't been thread safe (although it's a FreeBSD bug).
http://lists.freebsd.org/pipermail/freebsd-threads/2005-December/003333.html

and, the POSIX gods tell us "Failure to flush or close the file descriptor successfully shall be ignored.", so we could leak file descriptors or not get an error back to the user about being unable to finish their log file (however we do that without a log).

So a mutex seems to be the ticket.

same patch as for BUG#22313

marking as duplicate of BUG#22313