[8u40] Request for review (xs) : backport of 8034056 - assert(_heap_alignment >= _space_alignment) failed: heap_alignment less than space_alignment

[Jon Masamitsu]

This is a backport of 8034056.
https://bugs.openjdk.java.net/browse/JDK-8034056

This is the same fix that went into jdk9 but the
patch did not apply cleanly so I redid it.

http://cr.openjdk.java.net/~jmasa/8034056/webrev.00/