[Bug target/91638] powerpc -mlong-double-NN (documentation) issues

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91638

--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Yeah, not sure.  A user can just do `-mlong-double-128`, and will get whichever
128-bit format is the default.  That is the "old" way, when we only had the
ibm128 format, and it will be the new way too, when ibm128 has become a bad
dream and everything uses ieee128.

Maybe just something like

Use -mlong-double-128 for an 128-bit floating point format (either IEEE or
IBM)?