patch to make init_array work (2nd version; resend)

[Roland McGrath]

> I suppose it makes sense to put do_all_init() and do_all_fini() in a
> shared source file.  Do you want to do that or should I work on it?
> If the latter, just tell me where you want the functions.

I suppose csu/init.c makes sense.  I think you can make them static if you
use attribute_used so they are definitely there when the ld -r with start.o
is done.