[PATCH] gcc: implement AIX-style constructors

[CHIGOT, CLEMENT]

> Hi David, 
> 
> Here is the new version of the patch. 
> I've moved the startup function in crtcdtors files.
> 
> I'm just wondering if the part dealing with the
> __init_aix_libgcc_cxa_atexit is needed. I'm adding it because
> the destructor created in crtcxa.o is following GCC format and
> thus won't be launched if the flag "-mcdtors=aix" is passed.
> However, as you said, this option might not operate correctly
> if the GCC runtime isn't rebuild with it.

Gentle Ping. 

Thanks, 
Clément