[Bug target/71486] Transparent union doesn't work with long double for x86_64

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71486

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I thought the ABI for transparent unions was that of passing its members.

But int128 and long double are passed differently.