386 should force reserved CR0 bits set

[Octocontrabass]

In the PCx86 386 emulation, the reserved bits of CR0 are allowed to be cleared. On a real 386 (I've tested two, though they may have both been the same stepping), the reserved bits in CR0 are always set and can't be cleared.

You can verify by running ID.COM and comparing results against real hardware. Source is included.

I don't know of any software that relies on it aside from some AMI BIOSes, so it's probably not too important.

[jeffpar]

This should be fixed in the current release. PCx86 should now report the same results that my DeskPro 386/25 displays. Thanks for the test code.