umdns: add syscalls needed on Aarch64

Now that ujail supports seccomp also on Aarch64, add missing syscall
'fstat' to the list of allowed syscalls.

Signed-off-by: Daniel Golle <[email protected]>

package/network/services/umdns/files/umdns.json

@@ -24,6 +24,7 @@
 				"pipe",
 				"poll",
 				"fcntl64",
+				"fstat",
 				"epoll_create",
 				"epoll_create1",
 				"epoll_ctl",