unix: add MCAST_* consts on freebsd/arm

Change-Id: Iad1299fd440054c4522f0c7c96d2e0fb481685a6
Reviewed-on: https://go-review.googlesource.com/c/sys/+/305810
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/zerrors_freebsd_arm.go

diff --git a/unix/zerrors_freebsd_arm.go b/unix/zerrors_freebsd_arm.go
index 0326a6b..3df99f2 100644
--- a/unix/zerrors_freebsd_arm.go
+++ b/unix/zerrors_freebsd_arm.go
@@ -1022,6 +1022,15 @@
 	MAP_RESERVED0100               = 0x100
 	MAP_SHARED                     = 0x1
 	MAP_STACK                      = 0x400
+	MCAST_BLOCK_SOURCE             = 0x54
+	MCAST_EXCLUDE                  = 0x2
+	MCAST_INCLUDE                  = 0x1
+	MCAST_JOIN_GROUP               = 0x50
+	MCAST_JOIN_SOURCE_GROUP        = 0x52
+	MCAST_LEAVE_GROUP              = 0x51
+	MCAST_LEAVE_SOURCE_GROUP       = 0x53
+	MCAST_UNBLOCK_SOURCE           = 0x55
+	MCAST_UNDEFINED                = 0x0
 	MCL_CURRENT                    = 0x1
 	MCL_FUTURE                     = 0x2
 	MNT_ACLS                       = 0x8000000