Fixed or forbidden register was spilled

[Hans-Peter Nilsson]

> From: Bill Currie <bcurrie@tssc.co.nz>
> Date: Thu Nov 26 22:18:45 CET 1998

[Removed example of correct FD_ZERO asm using '&' constraint
modifier on output]

> I'm curious: what about the `+' modifier?  Is it more, or less,
> appropriate than `=&', or is it only a matter of asthetics? 

It was not valid for gcc-2.7.2, which might be an issue for
packages like glibc.

brgds, H-P