swift234

Add powerpc64le Linux support

This patch adds powerpc64le Linux support. While the patch also adds
the matching powerpc64 bits, there are endian issues that need to be
sorted out.

The PowerPC LLVM changes for the swift ABI (eg returning three element
non-homogeneous aggregates) are still in the works, but a simple LLVM
fix to allow those aggregates results in swift passing all but 8
test cases.