Update MSG_* constants

* xlat/msg_flags.in: Add MSG_BATCH.
diff --git a/xlat/msg_flags.in b/xlat/msg_flags.in
index 9369040..cf6b83c 100644
--- a/xlat/msg_flags.in
+++ b/xlat/msg_flags.in
@@ -15,6 +15,7 @@
 MSG_NOSIGNAL
 MSG_MORE
 MSG_WAITFORONE
+MSG_BATCH	0x40000
 MSG_EOF
 MSG_FASTOPEN
 MSG_CMSG_CLOEXEC