This adds definitions for contemporary processors
which may be selected via -cpu<model>, as an
alternative to the existing use of -cpu qemu64
augmented with a series of feature flags.
The primary motivation was determination of a
least common denominator within a given processor
class for simplification of guest migration. It
is still possible to modify an arbitrary model via
additional feature flags however the goal here was
to make doing so unnecessary in typical usage. The
other consideration was providing models names
reflective of current processors. Both AMD and
Intel have reviewed the models in terms of balancing
generality of migration vs. excessive feature
downgrade relative to released silicon.
A cpu feature 'check' option is also added which
warns when feature flags (either implicit in a cpu
model or explicit on the command line) would have
otherwise been quietly disabled for a guest.
This patch was tested relative to qemu-kvm.git.