util/getauxval: Porting to FreeBSD getauxval feature

util/getauxval: Porting to FreeBSD getauxval feature

From d7f9d40777d1ed7c9450b0be4f957da2993dfc72 Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Fri, 12 Jun 2020 09:39:17 +0100
Subject: [PATCH] util/getauxval: Porting to FreeBSD getauxval feature

FreeBSD has a similar API for auxiliary vector.

Signed-off-by: David Carlier <devnexen@gmail.com>
Message-Id: <CA+XhMqxTU6PUSQBpbA9VrS1QZfqgrCAKUCtUF-x2aF=fCMTDOw@mail.gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>