The warnings at the top of your build say oci8.c is missing. You cannot build DBD::Oracle without oci8.c (it is part of DBD::Oracle). This DBD::Oracle distribution seems fundamentally broken. I just downloaded DBD::Oracle 1.58 and it does contain oci8.c so the dir you are building DBD::Oracle in has been messed with. Untar it again and start from scratch.