internal/socket: add support for openbsd/riscv64

Updates golang/go#55999

Change-Id: Ib8b30b898821225ccf5502c7bb483accd950697c
Reviewed-on: https://go-review.googlesource.com/c/net/+/442756
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/internal/socket/zsys_openbsd_riscv64.go b/internal/socket/zsys_openbsd_riscv64.go
new file mode 100644
index 0000000..cebde76
--- /dev/null
+++ b/internal/socket/zsys_openbsd_riscv64.go
@@ -0,0 +1,30 @@
+// Code generated by cmd/cgo -godefs; DO NOT EDIT.
+// cgo -godefs defs_openbsd.go
+
+package socket
+
+type iovec struct {
+	Base	*byte
+	Len	uint64
+}
+
+type msghdr struct {
+	Name		*byte
+	Namelen		uint32
+	Iov		*iovec
+	Iovlen		uint32
+	Control		*byte
+	Controllen	uint32
+	Flags		int32
+}
+
+type cmsghdr struct {
+	Len	uint32
+	Level	int32
+	Type	int32
+}
+
+const (
+	sizeofIovec	= 0x10
+	sizeofMsghdr	= 0x30
+)