Warning: to be commited on "flag day"
This changes LLVM default powerpc64 ABI to ELFv2, if target OS is FreeBSD >= 13.0
This patch should be sent to upstream after flag day.
The change itself LGTM.
From a previous discussion these days, it seems the consensus was to propose it to LLVM upstream some time after FreeBSD itself commits the ELFv2 changes.
As this changes a previous default, I'm not sure if this change is eligible for backporting, but LLVM community knows better about it.