[8u] RFA: 8201495: [Zero] Reduce limits of max heap size for boot JDK on s390

[Severin Gehwolf]

Hi,

Please approve this backport of JDK-8201495 which reduces the max heap
requirement for the boot JDK of 32bit JVMs. It causes build failures of
the Zero variant JVM on s390 (31 bit, takes the 32bit branch). The fix
is in JDK 11, has been requested for JDK 10. The JDK 8 fix has been
reviewed on build-dev as the JDK 11 fix is slightly different due to
the different build systems.

Once approved, I'd need an Oracle sponsor to push this for me since it
requires re-generation of generated-configure.sh.

Bug: https://bugs.openjdk.java.net/browse/JDK-8201495
webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8201495/webrev.jdk8/
JDK 8 changeset (without generated-configure.sh):
http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8201495/JDK-8201495.jdk8.export.patch

JDK 8 review thread:
http://mail.openjdk.java.net/pipermail/build-dev/2018-May/021918.html

JDK 11 review thread was:
http://mail.openjdk.java.net/pipermail/build-dev/2018-April/021754.html

Thanks,
Severin