i386: Add Intel Processor Trace feature support

i386: Add Intel Processor Trace feature support

Expose Intel Processor Trace feature to guest.

To make Intel PT live migration safe and get same CPUID information
with same CPU model on diffrent host. CPUID[14] is constant in this
patch. Intel PT use EPT is first supported in IceLake, the CPUID[14]
get on this machine as default value. Intel PT would be disabled
if any machine don't support this minial feature list.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: Luwei Kang <luwei.kang@intel.com>
Message-Id: <1520182116-16485-1-git-send-email-luwei.kang@intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>