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

[Roland McGrath]

> OK, I _think_ I understand your concern.  Perhaps we could just change
> the platform-specific start.S to pass a different _init/_fini function
> which takes care of calling init_array/fini_array?  If you think that
> would work, I can take a stab at doing that for sysdeps/ia64/elf/start.S.

That seems like a reasonable thing to do, though it's unfortunate it means
changing all the platforms' start.S files.  For preinit_array+init_array,
start.S could just contain the code in the .init section, no?  But probably
it is better to write generic _init/_fini replacements in C.