`perldoc ExtUtils::Embed'

Now, running perl -MExtUtils::Embed -e xsinit on my old 5.6.1 perl gives

#include <EXTERN.h>
#include <perl.h>

EXTERN_C void xs_init (pTHXo);

EXTERN_C void boot_DynaLoader (pTHXo_ CV* cv);

EXTERN_C void
xs_init(pTHXo)
{
    char *file = __FILE__;
    dXSUB_SYS;

    /* DynaLoader is a special case */
    newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
}
[download]

I don't know if it will matter much (no c expert, dunno much about aix), but I'd try that using that instead of that xs_init(void) stuff. Also, your tiny error snippet is too tiny. You need to show how the compiler was invoked and all the messages it printed out (hopefully you're using ExtUtils::Embed for the compiler options).

update: Corion: s!EstUtils!ExtUtils!g