The function for_each_file_in_obj_subdir() takes a object subdirectory
number and expects the name of the same subdirectory to be included in
the path strbuf.  Avoid this redundancy by letting the function append
the hexadecimal subdirectory name itself.  This makes it a bit easier
and safer to use the function -- it becomes impossible to specify
different subdirectories in subdir_nr and path.
Suggested-by: NJeff King <peff@peff.net>
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>