hack/ostree_tag.sh: Fill in OSTree dependencies

Copying the libraries from:

  $ git grep pkg-config vendor/github.com/containers/image/
  vendor/github.com/containers/image/ostree/ostree_dest.go:// #cgo pkg-config: glib-2.0 gobject-2.0 ostree-1 libselinux
  vendor/github.com/containers/image/ostree/ostree_src.go:// #cgo pkg-config: glib-2.0 gobject-2.0 ostree-1

We need all of those to compile the vendored Go dependency, not just
ostree-1.

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #958
Approved by: giuseppe

hack/ostree_tag.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
-if ! pkg-config ostree-1 2> /dev/null ; then
+if ! pkg-config glib-2.0 gobject-2.0 ostree-1 libselinux 2> /dev/null ; then
 	echo containers_image_ostree_stub
 fi