cppfiles.c (struct include_file): Move from cpphash.h.
* cppfiles.c (struct include_file): Move from cpphash.h.
(_cpp_never_reread): New function.
(open_file, read_include_file): Use it.
(stack_include_file): Set the buffer's sysp according to the
path in which the file was found.
(find_include_file): Don't set sysp.
(cpp_make_system_header, actual_directory): Update.
(_cpp_execute_include): Do #include_next lookup handling here,
not in cpplib.c. Use _cpp_never_reread.
* cpphash.h (struct_include_file): Remove.
(struct cpp_buffer): New member sysp.
(CPP_IN_SYSTEM_HEADER, _cpp_execute_include): Update.
(_cpp_never_reread): New.
* cpplib.c (read_line_number): Rename read_flag. Rework slightly.
(end_directive): Clear line_extension flag.
(_cpp_handle_directive): Set line_extension flag for #number.
(do_include_next): Handle path lookup in _cpp_execute_include.
(do_line): Cleanup to use read_flag. Don't allow flags in #line.
(_cpp_do_file_change): Update.
(do_pragma_once): Use cpp_never_reread. Clean up.
* cpplib.h (struct lexer_state): New member line_extension.