Description of problem:
QEMU doesn't detect Core 2 Duo CPU.

Version-Release number of selected component (if applicable):
QEMU emulator version 0.15.1 (qemu-kvm-0.15.1) / qemu i686, 0.15.1-3.fc16

How reproducible:
Always.

Steps to Reproduce:
1.cat /proc/cpuinfo | grep model
2.qemu -cpu host -hda image.qcow -m 256
3.qemu -cpu ?
  
Actual results:
$ cat /proc/cpuinfo | grep model
model		: 23
model name	: Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
model		: 23
model name	: Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz
$ qemu -cpu host -hda image.qcow -m 256
Unable to find x86 CPU definition
$ qemu -cpu ?
x86           [n270]
x86         [athlon]
x86       [pentium3]
x86       [pentium2]
x86        [pentium]
x86            [486]
x86        [coreduo]
x86          [kvm32]
x86         [qemu32]
x86          [kvm64]
x86       [core2duo]
x86         [phenom]
x86         [qemu64]

Expected results:
QEMU started.