I was wondering why the three host_cpus i486, i586, and i686 have special treatment for the default setting as compared to all other cpu architectures?
I see this in configure.in
[ --enable-nonportable-atomics Use optimized atomic code which may produce nonportable binaries],
[if test $enableval = yes; then
[case $host_cpu in
i[]86) force_generic_atomics=yes ;;
*) force_generic_atomics=no ;;