syscall: add GetsockoptByte, SetsockoptByte for openbsd

R=golang-dev, fullung, dave, rsc
CC=golang-dev
https://golang.org/cl/5081044

src/pkg/syscall/syscall_bsd.go

@@ -363,6 +363,13 @@ func Socketpair(domain, typ, proto int) (fd [2]int, errno int) {
 	return
 }
 
+func GetsockoptByte(fd, level, opt int) (value byte, errno int) {
+	var n byte
+	vallen := _Socklen(1)
+	errno = getsockopt(fd, level, opt, uintptr(unsafe.Pointer(&n)), &vallen)
+	return n, errno
+}
+
 func GetsockoptInt(fd, level, opt int) (value, errno int) {
 	var n int32
 	vallen := _Socklen(4)
@@ -370,6 +377,11 @@ func GetsockoptInt(fd, level, opt int) (value, errno int) {
 	return int(n), errno
 }
 
+func SetsockoptByte(fd, level, opt int, value byte) (errno int) {
+	var n = byte(value)
+	return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(&n)), 1)
+}
+
 func SetsockoptInt(fd, level, opt int, value int) (errno int) {
 	var n = int32(value)
 	return setsockopt(fd, level, opt, uintptr(unsafe.Pointer(&n)), 4)