Followup to the 2007-02-12 patch, using suggestions from Bruno Haible in

Followup to the 2007-02-12 patch, using suggestions from Bruno Haible in
<http://lists.gnu.org/archive/html/bug-gnulib/2007-02/msg00136.html>.
* doc/gnulib-tool.texi (Initial import): Mention _FILE_OFFSET_BITS
as another example.
* lib/time_.h: Fix misspelling.
* m4/nanosleep.m4 (gl_FUNC_NANOSLEEP):
Require gl_HEADER_TIME_H_DEFAULTS.
* m4/strptime.m4 (gl_FUNC_STRPTIME): Likewise.
* m4/time_r.m4 (gl_TIME_R): Likewise.
* m4/timegm.m4 (gl_FUNC_TIMEGM): Likewise.