QEMU crashes when there is an "[accel]" section in the config file
Description of problem:
QEMU crashes with a segmentation fault if there is a "[accel]" section in the config file with a type="kvm" entry. It would be maybe still be OK if there was an error message instead, but it should certainly not crash.
Steps to reproduce:
```
$ cat > /tmp/config <<EOF
[accel]
type = "kvm"
EOF
$ qemu-system-x86_64 -readconfig /tmp/config
```