[9] RFR: 8168923: Use unsigned random long in a temp directory name

[Ivan Gerasimov]

Hello everyone!

When File.createTempFile() is called, a random long value is generated, 
which is then made positive with Math.abs() and then used as a part of 
the directory name.

Instead of using Math.abs() and Long.toString(), it would be better to 
use Long.toUnsignedString():
1) no need to deal with the corner case of Long.MIN_VALUE,
2) increase the space of random values by the factor of 2.

Would you please help review the fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8168923
WEBREV: http://cr.openjdk.java.net/~igerasim/8168923/00/webrev/

With kind regards,
Ivan