rootfs.py: Also uninstall update-alternatives and shadow for read-only-rootfs

This brings back commit d41097a970e9bfa553cd4bc3c9fad4b9073d7bd5,
which got lost during transition from image.bbclass to rootfs.py.

(From OE-Core rev: f4932e2e640764d16f1f6d398390ebfb376f4cf1)

Signed-off-by: Andreas Oberritter <obi@opendreambox.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oe/rootfs.py

@@ -190,6 +190,8 @@ class Rootfs(object):
                         pkg = pkg_installed.split()[0]
                         if pkg in ["update-rc.d",
                                 "base-passwd",
+                                "shadow",
+                                "update-alternatives",
                                 self.d.getVar("ROOTFS_BOOTSTRAP_INSTALL", True)
                                 ]:
                             pkgs_to_remove.append(pkg)