(basic_type_data): New global variable.
(basic_type): New function.
(parse_type): Remove static basic type map map_bt. Call basic_type
to get basic types instead of using mdebug_type_ variables.
(parse_symbol): Use builtin types instead of mdebug_type_ variables.
(upgrade_type): Likewise.
(parse_procedure): Likewise.
(psymtab_to_symtab_1): Likewise.
(_initialize_mdebugread): Do not initialize mdebug_type_ variables.
Initialize basic_type_data.