PR27725, better objcopy -p times

Nanosecond rather than second resolution.

	PR 27725
	* configure.ac: Check for sys/time.h and utimensat.  Use standard
	checks for mkstemp and mkdtemp.  Whitespace.  Check for nanosecond
	members of struct stat.
	* rename.c: Prefer sys/time.h for utimes over utime.h for utime.
	(STAT_TIMESPEC, STAT_TIMESPEC_NS): Define
	(get_stat_atime_ns, get_stat_mtime_ns): New inline functions.
	(get_stat_atime, get_stat_mtime): Likewise.
	(set_times): Choose first available of utimensat, utimes, utime.
	Use above inline functions to set timespec and timeval values.
	* configure: Regenerate.
	* config.in: Regenerate.
	* testsuite/binutils-all/objcopy.exp (objcopy_test): Add test of
	file timestamp when --preserve-dates is used.