unix: Add FADV_* constants
These constants are used for fadvise() on Linux and were missing from
the ztypes_linux_*.go files.
Including the bluetooth headers is necessary so that cgo can resolve
struct sockaddr_hci.
Fixes golang/go#15114
Change-Id: I1538b5a7b9b24f910c0520d446b2fa5bd8a09013
Reviewed-on: https://go-review.googlesource.com/21753
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>