/*
   * Create a relation.
   *
   * Equivalent to: Relation.new
   *
   * call-seq:
   *  pool.create_relation( "kernel" ) -> Relation
   *  pool.create_relation( "kernel", REL_GE, "2.6.26" ) -> Relation
   *
   */
  Relation *create_relation( const char *name, int op = 0, const char *evr = NULL )