Here's a patch that allow the user to specify a specific CPU
model/variant on the command line.
This makes different CPU tests less painfull, as the current code need a
recompilation for this.
This patch only has an actual effect when using the PowerPC target, as I
don't want to break other targets, but would be imho easy to implement
for all targets.
It just adds a -C <cpu_model> facultative option to the command line and
a new parameter to the machine->init callback. A machine can then ignore
this parameter or tune the emulated CPU based on the given CPU model.
Any comments will be welcome but I'd like to insist that such an option
would really be useful, at least for testing purposes.