RFR(XS): 8231403: [ppc]: Align ReservedCodeCacheSize default value with other platforms

[Schmidt, Lutz]

Dear all,

may I please request reviews for this tine change, aligning default settings on PPC with the rest of the world? There is no reason why PPC would need a 5x larger CodeCacheSize. Comparing actual utilization with other architectures shows only little variation.

Bug:    https://bugs.openjdk.java.net/browse/JDK-8231403
Webrev: https://cr.openjdk.java.net/~lucy/webrevs/8231403.00/

Test have been conducted SAP-internally only. Submit repo is of no help here because it is a PPC-only change.

Thanks,
Lutz