Provide ioctlPtr for all BSD platforms, then use this for BPF.
This reduces darwin specific code, as well as avoiding the use of
an indirect system call on OpenBSD.
Updates #63900
Change-Id: I81f3e74a3149150abe972f106903310e3cf26929
Reviewed-on: https://go-review.googlesource.com/c/go/+/540019
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Josh Rickmar <jrick@zettaport.com>