apparmor: add a features/policy dir to interface

Add a policy directory to features to contain features that can affect
policy compilation but do not affect mediation. Eg of such features would
be types of dfa compression supported, etc.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>

security/apparmor/apparmorfs.c

@@ -198,7 +198,12 @@ static struct aa_fs_entry aa_fs_entry_domain[] = {
 	{ }
 };
 
+static struct aa_fs_entry aa_fs_entry_policy[] = {
+	{}
+};
+
 static struct aa_fs_entry aa_fs_entry_features[] = {
+	AA_FS_DIR("policy",			aa_fs_entry_policy),
 	AA_FS_DIR("domain",			aa_fs_entry_domain),
 	AA_FS_DIR("file",			aa_fs_entry_file),
 	AA_FS_FILE_U64("capability",		VFS_CAP_FLAGS_MASK),