Which version of DBD::Oracle are you trying to install? Version 1.15 (I believe) allows trailing spaces on Oracle 9.2 VARCHAR2 fields. Alternatively, edit t/ph_type.pl to allow trailing spaces on VARCHAR2, i.e. change:

{ type=> 1, name=>"VARCHAR2", chops_space=>1, embed_nul=>1, skip=>0 },
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to

{ type=> 1, name=>"VARCHAR2", chops_space=>0, embed_nul=>1, skip=>0 },
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