pc-0.13 and older were missing some compat code that was present on
newer machine-types:

* x86_cpu_compat_disable_kvm_features(FEAT_1_ECX, CPUID_EXT_X2APIC);
  (pc-i440fx-1.7 and older)
  (added by commit ef02ef5f)
* x86_cpu_compat_set_features("n270", FEAT_1_ECX, 0, CPUID_EXT_MOVBE);
  (pc-i440fx-1.4 and older)
  (added by commit 4458c236
* x86_cpu_compat_set_features("Westmere", FEAT_1_ECX, 0, CPUID_EXT_PCLMULQDQ);
  (pc-i440fx-1.4 and older)
  (added by commit 56383703)

Instead of duplicating the code from the previous pc_compat_*()
functions, we can now reuse pc_compat_1_2() and fix those issues.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>