GCC 4.2 and previous have always warned about
"No newline at end of file".
Upstream GCC removed the warning completely but
Apple made it an optional warning. Adopt it for
compatibility with older GCC and clang.
While here, add comment to complement r258712.
Obtained from: Apple Inc. (Apple GCC 4.2 - 5531)
MFC after: 1 week
* lex.c (_cpp_clean_line): Add uses of __builtin_expect. Don't
look backward at the end of the line unless we saw a backslash.
* internal.h (struct cpp_reader): Add new fields:
nonexistent_file_hash and nonexistent_file_ob.
* files.c: Include "obstack.h".
(find_file_in_dir): Before trying to open the file, look up the
path name in the hash table of nonexistent files. After failing
to open the file, add the path name to the hash table.
(_cpp_find_file): Cache the results of looking up the file name
starting with the quote and bracket chain heads, if we can.
(nonexistent_file_hash_eq): New static function.
(_cpp_init_files): Initialize pfile->nonexistent_file_hash and
pfile->nonexistent_file_ob.
(_cpp_cleanup_files): Free pfile->nonexistent_file_hash and
pfile->nonexistent_file_ob.
Obtained from: gcc 4.3 (rev. 120263, 124929 ; GPLv2)
MFC after: 3 weeks
