RFR (S): 8237777 "Dumping core ..." is shown despite claiming that "# No core dump will be written."

[gerard ziemski]

hi all,

Please review this fix, where we use the knowledge available to us, like 
whether the ulimit is set, before deciding whether to tell the user in 
hs_err crash log that we dumped the core file, to match what actually 
happens.

Before this fix, we often assumed that the core file would be created, 
when in actuality that might not be the case.

I also extend an existing test to go with this fix.

bug: https://bugs.openjdk.java.net/browse/JDK-8237777
webrev: http://cr.openjdk.java.net/~gziemski/8237777_rev1
tests:  tested with Mach5 tier-hs1,2,3,4,5


cheers