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

[Alexander Smundak]

I've revised the patch to have fold little endian and big endian
PowerPC64 architectures.
The patch for the hotspot repository is at
http://cr.openjdk.java.net/~martin/asmundak/8036767/hotspot/webrev.01
Top-level build's OPENJDK_TARGET_CPU_ENDIAN variable is carried over
to the Hotspot build as ZERO_ENDIANNESS, so the patch takes advantage
of this to set target-dependend compiler flags in
make/linux/makefiles/ppc64.make.

The accompanying patches for the other repositories are at:
top-level: http://cr.openjdk.java.net/~martin/asmundak/8036767/webrev.01
jdk: http://cr.openjdk.java.net/~martin/asmundak/8036767/jdk/webrev.01