Better backwards compatibility for stat64.

Caused problems for some Google source switching to unified headers
because the legacy headers just used #define instead.

Bug: http://b/73210428
Test: builds
Change-Id: If8a36f284031e57af419903610029a8c34a23d91
diff --git a/libc/include/ftw.h b/libc/include/ftw.h
index 300f624..a289643 100644
--- a/libc/include/ftw.h
+++ b/libc/include/ftw.h
@@ -56,11 +56,9 @@
 
 __BEGIN_DECLS
 int ftw(const char* __dir_path, int (*__callback)(const char*, const struct stat*, int), int __max_fd_count) __INTRODUCED_IN(17);
-int nftw(const char* __dir_path, int (*__callback)(const char*, const struct stat*, int, struct FTW*), int __max_fd_count, int __flags)
-  __INTRODUCED_IN(17);
-int ftw64(const char* __dir_path, int (*__callback)(const char*, const struct stat64*, int), int __max_fd_count) __INTRODUCED_IN(21);
-int nftw64(const char* __dir_path, int (*__callback)(const char*, const struct stat64*, int, struct FTW*), int __max_fd_count, int __flags)
-  __INTRODUCED_IN(21);
+int nftw(const char* __dir_path, int (*__callback)(const char*, const struct stat*, int, struct FTW*), int __max_fd_count, int __flags) __INTRODUCED_IN(17);
+int ftw64(const char* __dir_path, int (*__callback)(const char*, const struct stat64*, int), int __max_fd_count) __RENAME_STAT64(ftw, 17, 21);
+int nftw64(const char* __dir_path, int (*__callback)(const char*, const struct stat64*, int, struct FTW*), int __max_fd_count, int __flags) __RENAME_STAT64(nftw, 17, 21);
 __END_DECLS
 
 #endif