[powerpc] fenvinline.h uses assembly modifier 's'

[Tim Shen]

...at here: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/powerpc/bits/fenvinline.h;hb=a3e5b4feeb54cb92657ec2bc6d9be1fcef9e8575#l45

The 's' modifier support is still in gcc 5 branch's
rs6000.c:print_operand, but not supported in the trunk. It's removed
by gcc patch r226005.

Is glibc the right place to fix this by not using %s0?

Thanks!

-- 
Regards,
Tim Shen