Add support for ppc64le (PowerPC 64bit little endian)
Submitted by Michel Normand
with orc 0.4.22 the make check is failing
investigation identified two related required changes:
to define HAVE_POWERPC for ppc64le.
to add support of ppc64le (that is PowerPC ABI V2)
at least epilog/prolog differs, but need to check all file.