RFR(S): 8194994: Remove redundant string streams used for logging

[Marcus Larsson]

Hi,

Please review the following patch to remove some redundant uses of 
string streams used for logging.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8194994/webrev.00/

Issue:
https://bugs.openjdk.java.net/browse/JDK-8194994

Tested with hs-tier 1-2.

Thanks,
Marcus