syscall: add bluetooth constants for linux

Tried to generate them with mkerrors.sh by including
bluetooth/bluetooth.h, but it introduces way much more
than necessary stuff.

Change-Id: I380f66892f55dbe4cbfc76a0e3f9817f81d269b9
Reviewed-on: https://go-review.googlesource.com/21675
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/bluetooth_linux.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Bluetooth sockets and messages
+
+package unix
+
+// Bluetooth Protocols
+const (
+	BTPROTO_L2CAP  = 0
+	BTPROTO_HCI    = 1
+	BTPROTO_SCO    = 2
+	BTPROTO_RFCOMM = 3
+	BTPROTO_BNEP   = 4
+	BTPROTO_CMTP   = 5
+	BTPROTO_HIDP   = 6
+	BTPROTO_AVDTP  = 7
+)
+
+const (
+	HCI_CHANNEL_RAW     = 0
+	HCI_CHANNEL_USER    = 1
+	HCI_CHANNEL_MONITOR = 2
+	HCI_CHANNEL_CONTROL = 3
+)
+
+// Socketoption Level
+const (
+	SOL_BLUETOOTH = 0x112
+	SOL_HCI       = 0x0
+	SOL_L2CAP     = 0x6
+	SOL_RFCOMM    = 0x12
+	SOL_SCO       = 0x11
+)