RFR(S): 8240634: event/runtime/TestMetaspaceAllocationFailure.java times out

[mikhailo.seledtsov at oracle.com]

This test timed out occasionally, about 1/100 runs, on Linux only. 
Please review this change that mitigates occasional test failure
by limiting the number of iterations attempting to fill up metaspace, 
and throwing SkippedException when the max number
of iterations is reached.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8240634
     Webrev: http://cr.openjdk.java.net/~mseledtsov/8240634.00/
     Testing:
         Ran 100 times on Linux, 1 skipped, rest PASS


Thank you,
Misha