Add bootstrap for powerpc64 elfv2.
Because of issue with macros in precompiled.hpp, --disable-precompiled-headers is necessary.
Since openjdk compiles for elfv1 by default on big-endian ppc64, use a patch to compile for elfv2.
I assume here that GCC will be used exclusively on ELFv1 systems and Clang on ELFv2.
PR: 243182
Approved by: glewis (maintainer)
* Re-roll bootstrap binaries. The main reason for this is that the
previous binaries won't work correctly on a FreeBSD 12/powerpc64
POWER8+ machine.
PR: 239368
