nulldfa.in makes for a very long unwrapped line, which certain tools
do not like. So add line breaks.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Instead of testing whether a given dfa exists in every code path, have
a default null dfa that is used when loaded policy doesn't provide a
dfa.
This will let us get rid of special casing and avoid dereference bugs
when special casing is missed.
Signed-off-by: John Johansen <john.johansen@canonical.com>