RFR: 8159695: Arguments::atojulong() fails to detect overflows

[Marcus Larsson]

Hi,

Please review the following patch to detect overflows in atojulong. The 
patch uses strtoull instead of sscanf, and adds a unit test for atojulong.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8159695/webrev.00/

Issue:
https://bugs.openjdk.java.net/browse/JDK-8159695

Testing:
JPRT testset hotspot and included unit test through RBT.

Thanks,
Marcus