RFR 8054095: No space allowed in platforms string in ProblemList.txt

[Amy Lu]

Please review the problem list change for JDK-8054095
http://cr.openjdk.java.net/~ewang/amylu/JDK-8054095/webrev.00/

In ProblemList.txt, when specify multiple platforms, the space between the 
platform names is not accepted by jtreg harness.
This change is to remove the empty space between the platform names.
 
Thanks,
Amy