Description of problem:
Starting a VM using QXL as Video device fails to start.

Version-Release number of selected component (if applicable):
2:5.1.0-1.fc34   qemu-kvm
2:5.1.0-1.fc34   qemu-device-display-qxl

How reproducible:
I don't know, on my computer, 100%

Steps to Reproduce:
1. Start Virt-manager
2. Select any VM
3. click on details
4. click on Video ${vga_device}
5. Having qxl as video device fails to start VM
6. Changing the video back to QXL fails

Actual results:
```
Error changing VM configuration: unsupported configuration: domain configuration does not support 'video model' value 'qxl'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/addhardware.py", line 364, in change_config_helper
    define_func(devobj=devobj, do_hotplug=False, **define_args)
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 758, in define_video
    self._redefine_xmlobj(xmlobj)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 417, in _redefine_xmlobj
    self._redefine_xml_internal(origxml, newxml)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 395, in _redefine_xml_internal
    self._define(newxml)
  File "/usr/share/virt-manager/virtManager/object/domain.py", line 999, in _define
    self.conn.define_domain(xml)
  File "/usr/share/virt-manager/virtManager/connection.py", line 612, in define_domain
    return self._backend.defineXML(xml)
  File "/usr/lib64/python3.9/site-packages/libvirt.py", line 4063, in defineXML
    if ret is None:raise libvirtError('virDomainDefineXML() failed', conn=self)
libvirt.libvirtError: unsupported configuration: domain configuration does not support 'video model' value 'qxl'
```

Expected results:
VM Starts without having issues

Additional info:
outputs of "qemu-system-x86_64"
```
qemu-system-x86_64 -vga qxl
Failed to open module: /usr/lib64/qemu/ui-gtk.so: undefined symbol: qemu_xkeymap_keycodes_semaphore
Failed to open module: /usr/lib64/qemu/ui-sdl.so: undefined symbol: qemu_xkeymap_keycodes_semaphore
Failed to open module: /usr/lib64/qemu/hw-display-qxl.so: undefined symbol: qemu_qxl_client_monitors_config_crc_semaphore
qemu-system-x86_64: QXL VGA not available
```