cpu_map.xml: Expand 486 CPU model

Inheritance among CPU model is cool but it makes reviewing CPU model
definitions and comparing them to CPU models from QEMU rather hard and
unpleasant. Let's define all CPU models from scratch.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

src/cpu/cpu_map.xml

@@ -341,13 +341,15 @@
 
     <!-- Intel-based QEMU generic CPU models -->
     <model name='pentium'>
-      <model name='486'/>
       <feature name='cx8'/>
       <feature name='de'/>
+      <feature name='fpu'/>
       <feature name='mce'/>
       <feature name='mmx'/>
       <feature name='msr'/>
+      <feature name='pse'/>
       <feature name='tsc'/>
+      <feature name='vme'/>
     </model>
 
     <model name='pentium2'>