This adds the options: seuser, serole, setype, and serange to the file
module.  If the python selinux module doesn't exist, this will set
HAVE_SELINUX to False and punt in the related modules.

This takes the options the user provides and applies those to the
default selinux context as provided from matchpathcon().  If there is no
default context, this uses the value from the current context.  This
implies that if you set the setype and later remove it, the file module
will rever the setype to the default if available.