[Bug target/91886] [10 regression] powerpc64 impossible constraint in asm

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91886

--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Yes, you should use "wa".

Making our constraint (and output modifier) doc more useful is on my list
for GCC 10.