We now pass a pointer to the context where necessary. There are a
few cases where we need to request the context from sudoers via
sudoers_get_context() for the plugin API functions. If the plugin
API was able to pass around a closure pointer this would not be
necessary.
This adds audit plugin support to the sudoers module, currently
only used for accept events. As a result, the sudoers file is now
initially parsed as an audit plugin.
