Add Core 2 Duo CPU specification v3

Hi,

this set of patches attempts to implement a CPU definition set for current Intel CPUs that resembles an original as closely as currently possible. Several features a current Intel CPU has are not implemented by qemu, but that should not keep us from adding this definition so people can add features later on.

As a side effect, I made the sysenter instruction 64-bit aware. This was an issue in KVM, that used the 32-bit cpu struct variables to hold 64-bit MSR values sysenter needs. I believe it to be a step in the right direction to not fix this only for KVM, but make the functionality available to qemu as well.

Version 2 adds save/load. Only the sysenter implementation has changed. Version 3 pushes the series from -p2 to -p1

Alex