unix: add ICMPV6_FILTER_* consts on linux

Change-Id: If626dab3c708d78768ae593b7b3f8bff280ee641
Reviewed-on: https://go-review.googlesource.com/c/sys/+/305049
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/mkerrors.sh

diff --git a/unix/mkerrors.sh b/unix/mkerrors.sh
index 086d694..f2bc863 100755
--- a/unix/mkerrors.sh
+++ b/unix/mkerrors.sh
@@ -502,7 +502,7 @@
 		$2 ~ /^(AF|SOCK|SO|SOL|IPPROTO|IP|IPV6|ICMP6|TCP|MCAST|EVFILT|NOTE|SHUT|PROT|MAP|MFD|T?PACKET|MSG|SCM|MCL|DT|MADV|PR|LOCAL)_/ ||
 		$2 ~ /^TP_STATUS_/ ||
 		$2 ~ /^FALLOC_/ ||
-		$2 ~ /^ICMP(V6)?_FILTER$/ ||
+		$2 ~ /^ICMP(V6)?_FILTER/ ||
 		$2 == "SOMAXCONN" ||
 		$2 == "NAME_MAX" ||
 		$2 == "IFNAMSIZ" ||

unix/zerrors_linux.go

diff --git a/unix/zerrors_linux.go b/unix/zerrors_linux.go
index 3b1b928..35de419 100644
--- a/unix/zerrors_linux.go
+++ b/unix/zerrors_linux.go
@@ -974,6 +974,10 @@
 	HUGETLBFS_MAGIC                             = 0x958458f6
 	IBSHIFT                                     = 0x10
 	ICMPV6_FILTER                               = 0x1
+	ICMPV6_FILTER_BLOCK                         = 0x1
+	ICMPV6_FILTER_BLOCKOTHERS                   = 0x3
+	ICMPV6_FILTER_PASS                          = 0x2
+	ICMPV6_FILTER_PASSONLY                      = 0x4
 	ICMP_FILTER                                 = 0x1
 	ICRNL                                       = 0x100
 	IFA_F_DADFAILED                             = 0x8