AppleHV enablement pass #2

* Use vfkit command line assembly
* Inject ignition file into guest using http over vsock
* Ready notification through use of vsock

[NO NEW TESTS NEEDED]

Signed-off-by: Brent Baude <bbaude@redhat.com>

vendor/github.com/twitchyliquid64/golang-asm/bio/must.go

@@ -0,0 +1,43 @@
+// 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.
+
+package bio
+
+import (
+	"io"
+	"log"
+)
+
+// MustClose closes Closer c and calls log.Fatal if it returns a non-nil error.
+func MustClose(c io.Closer) {
+	if err := c.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+// MustWriter returns a Writer that wraps the provided Writer,
+// except that it calls log.Fatal instead of returning a non-nil error.
+func MustWriter(w io.Writer) io.Writer {
+	return mustWriter{w}
+}
+
+type mustWriter struct {
+	w io.Writer
+}
+
+func (w mustWriter) Write(b []byte) (int, error) {
+	n, err := w.w.Write(b)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return n, nil
+}
+
+func (w mustWriter) WriteString(s string) (int, error) {
+	n, err := io.WriteString(w.w, s)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return n, nil
+}