RFR(xxxs): 8245707: Increase Metaspace reserve alignment

[Thomas Stüfe]

Hi all,

may I have reviews for this tiny change:

JBS: https://bugs.openjdk.java.net/browse/JDK-8245707
webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8245707-increase-metaspace-reserve-alignment/webrev.00/webrev/

One of the motivations behind JDK-8243392 was to decouple CDS reservation
alignment from metaspace alignment and prevent misuse of metaspace reserve
alignment outside metaspace. This is needed since with the upcoming new
metaspace (JDK-8221173) its reserve alignment requirement will be much
higher than CDS alignment.

For the time being, until JDK-8221173 finds its way into jdk mainline, we
should increase metaspace reserve alignment in jdk mainline to trigger any
remaining illegal uses of metaspace reserve alignments and to prevent new
ones from creeping in.

All CI tests at SAP went through successfully, so at the moment we seem to
be clean.

Thanks, Thomas