The VIR_ERR_NO_SUPPORT refers to an API which is not implemented.
There is a separate VIR_ERR_CONFIG_UNSUPPORTED for XML config
options that are not available with the current hypervisor.

* src/qemu/qemu_conf.c, src/qemu/qemu_driver.c: Remove
  many VIR_ERR_NO_SUPPORT replace with VIR_ERR_CONFIG_UNSUPPORTED