Currently our default 32-bit CPU on Linux and Windows is "pentium4" which comes with pentium4 tuning settings and almost non-existent scheduler.
This patch proposes to add a 32-bit CPU with sse2, but with more modern tuning settings to replace the default pentium4. I've chosen this way so that -march=pentium4 behavior doesn't change. Alternatively we can just change the pentium4 settings and assume no one cares about truly tuning for pentium4 these days.
This would be unnecessary if -mtune were supported, but this is a lot less effort than plumbing mtune.