Import filemode module from gnulib.

Import filemode module from gnulib.

* .bzrignore: Add lib/sys/.
* Makefile.in (GNULIB_MODULES): Add filemode.
* lib/Makefile.am (MOSTLYCLEANDIRS): New macro.
* lib/filemode.c: Renamed from src/filemode.c and regenerated
from gnulib.  This adds support for some more file types, e.g.,
Cray DMF migrated files.
* lisp/emacs-lisp/find-gc.el (find-gc-source-files): Remove filemode.c.
* lib/filemode.h, lib/sys_stat.in.h, m4/filemode.m4, m4/st_dm_mode.m4:
* m4/sys_stat_h.m4: New files, generated from gnulib.
* aclocal.m4, configure, lib/Makefile.in, lib/gnulib.mk, m4/gl-comp.m4:
Regenerate.

2011-02-20  Paul Eggert  <eggert@cs.ucla.edu>