iocLogClient and atExit crash

[<freddie.akeroyd@stfc.ac.uk>]

Hi,

I had an IOC crash during exiting while in logClientSend() - errlogThread() was trying to send a message after logClientDestroy() had already been called by epicsExitCallAtExits(). I was able to remove the crash by adding the line:

	epicsAtExit(errlogRemoveListener, (void*)listener);

to the end of the errlogAddListener() function so that the log client is removed from the listener list before it is destroyed. I hope that is the correct fix. 

This was running base 3.14.12.4 on window x64 compiled with VS 2010

Regards,

Freddie