unix: add additional illumos STREAMS ioctls

This work is in support of WireGuard/wireguard-go#39

Change-Id: I04f3fdb40c1a6c8fe42cab5253c9edd4a5a1845d
Reviewed-on: https://go-review.googlesource.com/c/sys/+/348950
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Than McIntosh <thanm@google.com>
diff --git a/unix/types_illumos.go b/unix/types_illumos.go
index 770f8aa..d47ab63 100644
--- a/unix/types_illumos.go
+++ b/unix/types_illumos.go
@@ -33,6 +33,8 @@
 	I_STR     = C.I_STR
 	I_POP     = C.I_POP
 	I_PUSH    = C.I_PUSH
+	I_LINK    = C.I_LINK
+	I_UNLINK  = C.I_UNLINK
 	I_PLINK   = C.I_PLINK
 	I_PUNLINK = C.I_PUNLINK
 
diff --git a/unix/ztypes_illumos_amd64.go b/unix/ztypes_illumos_amd64.go
index 236f37e..4c48526 100644
--- a/unix/ztypes_illumos_amd64.go
+++ b/unix/ztypes_illumos_amd64.go
@@ -13,6 +13,8 @@
 	I_STR     = 0x5308
 	I_POP     = 0x5303
 	I_PUSH    = 0x5302
+	I_LINK    = 0x530c
+	I_UNLINK  = 0x530d
 	I_PLINK   = 0x5316
 	I_PUNLINK = 0x5317