RFR (M): 8036767 PPC64: Support for little endian execution model

[Alexander Smundak]

This patch contains the changes to the build files to build JDK on the
little endian PowerPC64 running Linux, and the changes to the source
files to support little endian mode.
The preceding related change:
https://bugs.openjdk.java.net/browse/JDK-8036767
added support for the ELFv2 ABi used on the little endian PowerPC64.

Please review and test this change. I need a sponsor.

The patch is at:
http://cr.openjdk.java.net/~martin/asmundak/8036767/webrev.00/

Sasha