The make compiles successfully for me given your environment of AIX 5.3. I particularly feel that there is something wrong with the environment settings. Can you please provide me the output for the following:-

Versions of DBI and DBD:DB2 installed and if you have any environment settings related to DB2. It would be really great if you can provide me steps of how you are proceeding with the install. I would try to replicate the same environment.