RFR (M): 8035647 : PPC64: Support for elf v2 abi.

[Alexander Smundak]

This patch adds support for the recently introduced ELFv2 ABI
for the PowerPC64.
The patch was generated for the jdk9/hs-rt/hotspot repository
(the same patch has been already committed to the ppc-aix-port/jdk7u).
It should for to jdk8u via ppc-aix-port/stage.

This patch is ppc-only.

ELFv2 ABI has been introduced recently and is used on by Linux running on
the little endian PowerPC64. There is no official ELF ABI supplement for it,
but the differences with "old" ABI for PowerPC64 are explained in the
comments for the patches to the GCC compiler:
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01144.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01141.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01140.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01145.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01147.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01149.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01146.html
http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01150.html

The change that affects JVM most is the elimination of the function
descriptors (which unfortunately requires introducing a number of #ifdef's
into the code), and dropping two words from the base frame (which
required mostly renaming of the structs from `abi_48' to a more neutral
`abi_minframe', etc.)

There are additional patches needed to fully support building
JDK on the little endian PowerPC64; RFRs for them will follow.

The development was done on Ubuntu 14.04 running on QEMU.
With all the patches applied, I can build working JDK7 and JDK9 there.

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

The patch is at:
http://cr.openjdk.java.net/~rasbold/8035647/webrev.00/

Sasha