postgresql compile problem

Hi,
Eecently, I have downloaded the postgresql-8.1.9.tar.gz from the official website,and then I install in my linux System
,whosegcc version is 2.9.6.Although I can install it successfully,then result version I check is 7.2.1~��and how can
thishappen,can u tell me the reason?
 

Thanks a lot !

Regards
--                                                                                                                Cai
jun