OpenBSD: Disable readV (#5786)

https://github.com/XTLS/Xray-core/pull/5784#issuecomment-4024880917
https://github.com/XTLS/Xray-core/issues/5756#issuecomment-4015530258
https://github.com/XTLS/Xray-core/pull/5824#issuecomment-4103829456

common/buf/readv_posix.go

@@ -1,5 +1,5 @@
-//go:build !windows && !wasm && !illumos
-// +build !windows,!wasm,!illumos
+//go:build !windows && !wasm && !illumos && !openbsd
+// +build !windows,!wasm,!illumos,!openbsd
 
 package buf
 

common/buf/readv_reader.go

@@ -1,5 +1,5 @@
-//go:build !wasm
-// +build !wasm
+//go:build !wasm && !openbsd
+// +build !wasm,!openbsd
 
 package buf
 

common/buf/readv_reader_stub.go

@@ -0,0 +1,17 @@
+//go:build wasm || openbsd
+// +build wasm openbsd
+
+package buf
+
+import (
+	"io"
+	"syscall"
+
+	"github.com/xtls/xray-core/features/stats"
+)
+
+const useReadv = false
+
+func NewReadVReader(reader io.Reader, rawConn syscall.RawConn, counter stats.Counter) Reader {
+	panic("not implemented")
+}

common/buf/readv_reader_wasm.go

@@ -1,15 +0,0 @@
-//go:build wasm
-// +build wasm
-
-package buf
-
-import (
-	"io"
-	"syscall"
-)
-
-const useReadv = false
-
-func NewReadVReader(reader io.Reader, rawConn syscall.RawConn) Reader {
-	panic("not implemented")
-}

common/buf/readv_test.go

@@ -1,5 +1,5 @@
-//go:build !wasm
-// +build !wasm
+//go:build !wasm && !openbsd
+// +build !wasm,!openbsd
 
 package buf_test