sudo: fix install

Running sudo on the target fails with the following errors.

  sudo: /usr/libexec/sudoers.so: No such file or directory
  sudo: fatal error, unable to load plugins

The problem is that the installation of the sudo package is broken. This patch
replaces the hand-crafted install rule with the default AUTOTARGETS install.

Unfortunately, the default install fails because it includes a step that
invokes the cross-compiled visudo binary. A patch is provided here to disable
this visudo invocation, which is for sanity checking only. This local patch is
a backport of upstream commit 8209:0c4e3f68b2f5; the real fix will be in the
1.8.6 release of sudo.

Signed-off-by: Simon Dawson <spdawson@gmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>