Adapted the default sudo_printf from sudoers plugin to be able to print
errors before plugin open() gets called. (This is used by the multiple io
plugin loading to display error for too much plugin load.)
Since this makes us always have a sudo_log, I have removed the logic about
whether it is available or not.
They are platform dependant, so their test would fail on some platforms.
While we could create separate plugin for the tests, I like the idea that
the examples are ensured to be working.
I believe this is a good compromise for being able to auto update the
test cases.
