RFR: 8150894: Unused -Xlog tag sequences are silently ignored.

[Marcus Larsson]

Hi,

Please review the following patch to add a warning for when tag 
selections in -Xlog or VM.log don't match any tag sets used in the VM.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8150894/webrev.00/

Issue:
https://bugs.openjdk.java.net/browse/JDK-8150894

Testing:
Internal VM tests with RBT

Thanks,
Marcus