8230645: CDS regions get loaded with the wrong alignment

[Thomas Stüfe]

Hi,

may I have reviews for this tiny fix please. CDS requires that its regions
are loaded with metaspace alignment - I am not sure why. But when loading,
it aligns loaded regions with alloc granularity.

Since metaspace reserve alignment is usually alloc granularity, this is
only a problem when one plays around with metaspace, in which case CDS
asserts on startup.

Bug: https://bugs.openjdk.java.net/browse/JDK-8230645
webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8230645-cds-regions-get-loaded-with-wrong-alignment/webrev.00/webrev/

Note that I am not sure why CDS uses metaspace reserve alignment at all. I
do not see a reason for this since metaspace reserve alignment does not
affect CDS regions?

Thanks, Thomas