qemu_namespace: Tolerate missing ACLs when creating a path in namespace

When creating a path in a domain's mount namespace we try to set
ACLs on it, so that it's a verbatim copy of the path in parent's
namespace. The ACLs are queried upfront (by
qemuNamespaceMknodItemInit()) but this is fault tolerant so the
pointer to ACLs might be NULL (meaning no ACLs were queried, for
instance because the underlying filesystem does not support
them). But then we take this NULL and pass it to virFileSetACLs()
which immediately returns an error because NULL is invalid value.

Mimic what we do with SELinux label - only set ACLs if they are
non-NULL which includes symlinks.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_namespace.c

@@ -1040,8 +1040,7 @@ qemuNamespaceMknodOne(qemuNamespaceMknodItem *data)
         goto cleanup;
     }
 
-    /* Symlinks don't have ACLs. */
-    if (!isLink &&
+    if (data->acl &&
         virFileSetACLs(data->file, data->acl) < 0 &&
         errno != ENOTSUP) {
         virReportSystemError(errno,