RFR (S): 8025427 jstat tests fails on 32-bit platforms

[Staffan Larsen]

This change makes jstat output '-' instead of '\ufffd' when the result of a calculation is NaN. '\ufffd' is typically not displayable in a terminal. 

This change also updates the tests to allow '-' as the output int the CCS (Compressed Class Space Space - Percent Used) column from -gcutil and -gccause. It can be hard to see from the diff but what I have done is change the regexp for that column from:

[0-9]+\.[0-9]+

to:

([0-9]+\.[0-9]+)|-

Testing: Passes tests locally, currently running JPRT.

webrev: http://cr.openjdk.java.net/~sla/8025427/webrev.00/
bug: https://bugs.openjdk.java.net/browse/JDK-8025427

Thanks,
/Staffan