qemu: Return -EINVAL to keep qemuDomainOpenFile() consistent

The description of the function says that the return value is a
file descriptor on success and negative errno on failure which is
not true. If the 'if' case with check on security labels fails,
the return value is -1 not -errno. The solution is to return
'-EINVAL' instead.

Signed-off-by: Kristina Hanicova <khanicov@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_domain.c

@@ -11509,7 +11509,7 @@ qemuDomainOpenFile(virQEMUDriver *driver,
         (seclabel = virDomainDefGetSecurityLabelDef(vm->def, "dac")) != NULL &&
         seclabel->label != NULL &&
         (virParseOwnershipIds(seclabel->label, &user, &group) < 0))
-        return -1;
+        return -EINVAL;
 
     return virQEMUFileOpenAs(user, group, dynamicOwnership,
                              path, oflags, needUnlink);