audit: add syscall information to CONFIG_CHANGE records

Tie syscall information to all CONFIG_CHANGE calls since they are all a
result of user actions.

Exclude user records from syscall context:
Since the function audit_log_common_recv_msg() is shared by a number of
AUDIT_CONFIG_CHANGE and the entire range of AUDIT_USER_* record types,
and since the AUDIT_CONFIG_CHANGE message type has been converted to a
syscall accompanied record type, special-case the AUDIT_USER_* range of
messages so they remain standalone records.

See: https://github.com/linux-audit/audit-kernel/issues/59
See: https://github.com/linux-audit/audit-kernel/issues/50

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: fix line lengths in kernel/audit.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/audit_fsnotify.c

@@ -127,7 +127,7 @@ static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, c
 
 	if (!audit_enabled)
 		return;
-	ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
+	ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
 	if (unlikely(!ab))
 		return;
 	audit_log_session_info(ab);