RFR(S): 8198554: Add fuzzy matching for log levels and tags when parsing -Xlog

[Marcus Larsson]

Hi,

Please review the following patch to add some fuzzy matching to improve 
-Xlog parsing error messages. The implementation of the fuzzy -XX flag 
matching is moved out to StringUtils so it can be re-used here.

Issue:
https://bugs.openjdk.java.net/browse/JDK-8198554

Webrev:
http://cr.openjdk.java.net/~mlarsson/8198554/webrev.00

Tested with hs-tier 1-2.

Thanks,
Marcus