Request for Review (s) - 8135318: CMS wrong max_eden_size for check_gc_overhead_limit

[Jon Masamitsu]

This fixes a bug in the CMS calculation that is used to
check the GC overhead limit.  The max size of eden was
incorrectly calculated as the young gen size - 2 * survivor
space size.  The young gen size only includes 1 survivor space
so only 1 should have been subtracted.  The fix uses the young
generation max_eden_size() that does the calculation correctly.

Fix was contributed by ivan.galkin at sap.com

Ivan, please check that the patch is correct.


CR: https://bugs.openjdk.java.net/browse/JDK-8135318
webrev: http://cr.openjdk.java.net/~jmasa/8135318/webrev.00/

Thanks.

Jon