RFR: 8145083: Use semaphore instead of mutex for synchronization of Unified Logging configuration

[Marcus Larsson]

Hi,

Please review the following patch to use a semaphore instead of a mutex 
for the synchronization of log configuration. Using a mutex requires 
some parts of the VM to be initialized, whereas the semaphores can be 
used right from the start. This simplifies the code and allows very 
early log configuration without special cases for early configuration vs 
reconfiguration after VM init.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8145083/webrev.00/

Issue:
https://bugs.openjdk.java.net/browse/JDK-8145083

Thanks,
Marcus