gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h

         - Add definition for c_finish_oacc_host_data().

     gcc/cp/parser.c b/gcc/cp/parser.c

         - Add handling of use_device clause in cp_parser_omp_clause_name().
         - Add handling of use_device clause in cp_parser_oacc_all_clauses().
         - Add new macro OACC_HOST_DATA_CLAUSE_MASK.
         - Add new function cp_parser_oacc_host_data() to handle host_data.
         - Add handling of host_data pragma to cp_parser_omp_construct().
         - Add handling of host_data pragma to cp_parser_pragma().

     gcc/cp/semantics.c b/gcc/cp/semantics.c

         - Add handling of use_device clause to finish_omp_clauses().
         - Add new function finish_oacc_host_data().