Add warnings for #directives with indented #

[Neil Booth]

Hi Zack

Zack Weinberg wrote:-
> ===================================================================
> Index: testsuite/gcc.dg/cpp-tradwarn1.c
> --- testsuite/gcc.dg/cpp-tradwarn1.c	Tue May  5 13:32:27 1998
> +++ testsuite/gcc.dg/cpp-tradwarn1.c	Sat Apr  1 14:42:31 2000

Can we use longer than 8.3 names?  I saw a message about not doing so
somewhere.  I hope so, as I'd like to for my test files.

Neil.