umdns: add missing syscall to seccomp filter

There is some syscall missing:
'getdents64'
'getrandom'
'statx'
'newfstatat'

Found with:
'mkdir /etc/umdns; ln -s /tmp/1.json /etc/umdns/; utrace /usr/sbin/umdns'

Signed-off-by: Chen Minqiang <[email protected]>

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

@@ -19,12 +19,15 @@
 				"fcntl",
 				"fcntl64",
 				"fstat",
+				"getdents64",
 				"getsockname",
+				"getrandom",
 				"ioctl",
 				"madvise",
 				"mmap",
 				"mmap2",
 				"munmap",
+				"newfstatat",
 				"open",
 				"openat",
 				"pipe",
@@ -42,6 +45,7 @@
 				"setsockopt",
 				"sigreturn",
 				"socket",
+				"statx",
 				"time",
 				"uname",
 				"write",