RFR(S): 7901696: os.simpleArch is x64 for linux-ppc64le in @require context

[Lindenmaier, Goetz]

Hi

Equivalent to https://bugs.openjdk.java.net/browse/CODETOOLS-7901514
I need to test for ppc64le.
We also run jtreg test with SAP JVM on zArch/s390, so I would like to fix this,
too.  When building, I found the doku wrong.

Please review this fix.  Do I need a sponsor, or may I push myself?
http://cr.openjdk.java.net/~goetz/wr16/7901696-jtregFixRequires/

Best regards,
  Goetz.