Ignore the anonymous monk saying your LD_LIBRARY_PATH is wrong because you cannot get an Oracle.so if you have an undefined symbol because you can.
charsetid is an extern referred to in dbdimp.h
extern ub2 charsetid;
I don't think I've tried 11.2.0.3. Do any of the headers or shared objects included in the build but from you Oracle client install mention charsetid? (you can use nm -a to show symbols in shared objects). I will download the latest instant client and try it myself.
Why are you building an old DBD::Oracle? - the latest is 1.64.
UPDATE: sorry, charsetid is defined in DBD::Oracle's dbdimp.c