Use the 'chardev-backends' test data as symlink to invoke the test case
again asserting QEMU_CAPS_CHARDEV_JSON which will make the commandline
generator use the JSON representation of the -chardev backend instead
allowing us to validate it agains the QMP schema.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
