you say :

The version of perl we are using (at this point) is 5.005_2 and 5.005_3 on Solaris 5.6 and 5.5.1.

from a mailing list message :

>  C Source Incompatibilities
>
>    `PERL_POLLUTE'
>        Release 5.005 grandfathered old global symbol names by
>        providing preprocessor macros for extension source
>        compatibility. As of release 5.6, these preprocessor
>        definitions are not available by default. You need to
>        explicitly compile perl with `-DPERL_POLLUTE' to get these
>        definitions. For extensions still using the old symbols,
>        this option can be specified via MakeMaker:
>
>            perl Makefile.PL POLLUTE=1

So it would seem that POLLUTE=1 is a workaround for newer perls (5.6) to get along with modules that require older perl bits (5.005). Ask whoever told you to use POLLUTE=1 (why hadn't you asked them to start with?) what version of perl they tested kstat with. It may be possible you don't need it at all.
Update : when I say "it may be possible you don't need it at all" I meant as opposed to upgrading to a 5.6 perl. There's no reason why anyone should've guessed that, though.