[Bug target/71806] PowerPC -mcpu=power9 enables __float128 without an explicit -mfloat128

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71806

--- Comment #1 from Michael Meissner <meissner at gcc dot gnu.org> ---
Created attachment 38860
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38860&action=edit
Proposed patch to fix the problem