RFR: 8147348: LogTagLevelExpression not properly initialized in configure_stdout

[Marcus Larsson]

Hi,

Please review the following patch to fix an initialization error in 
LogTagLevelExpression. If not using the parse() method (as is the case 
in LogConfiguration::configure_stdout) instances of the class would not 
be properly initialized.

The clear() method has been removed and the necessary initialization is 
now done in the constructor instead. An internal VM test has been added 
for configure_stdout.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8147348/webrev.00/

Issue:
https://bugs.openjdk.java.net/browse/JDK-8147348

Testing:
New test through JPRT

Thanks,
Marcus