Error out on unhandled parts when parsing a profile

... (using `%option nodefault`) instead of echoing the unknown parts to
stdout, and ignoring the error.

This will cause the parser to error out with

    flex scanner jammed

and $?=2 if a profile contains unknown/invalid parts. That's not really
a helpful error message, but still better than ignoring errors.

MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/569
Signed-off-by: Christian Boltz <apparmor@cboltz.de>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <sbeattie@ubuntu.com>
(cherry picked from commit c01ed1d57b)

parser/parser_lex.l

@@ -24,6 +24,7 @@
 %option noyywrap
 %option nounput
 %option stack
+%option nodefault
 
 %{
 #include <stdio.h>