RFR: 8206470: Incorrect use of os::lasterror in ClassListParser

[patricio.chilano.mateo at oracle.com]

Hi all,

Could you please review this small change?

Summary: The change is for future-proof the code in case errno gets 
overwritten inside the allocation logic.

Bug URL: https://bugs.openjdk.java.net/browse/JDK-8206470
Webrev URL: 
http://cr.openjdk.java.net/~coleenp/8206470.01/webrev/index.html 
<http://cr.openjdk.java.net/%7Ecoleenp/8206470.01/webrev/index.html>

Thanks,
Patricio