move iterate_on_dir() from e2fsprogs to libbb

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

e2fsprogs/e2fs_lib.h

@@ -11,11 +11,6 @@
 
 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
-/* Iterate a function on each entry of a directory */
-int iterate_on_dir(const char *dir_name,
-		int FAST_FUNC (*func)(const char *, struct dirent *, void *),
-		void *private);
-
 /* Print file attributes on an ext2 file system */
 void print_e2flags_long(unsigned flags);
 void print_e2flags(unsigned flags);