bulk_create_paths was inspired by createmany when it was outputting
status lines every 10000 files. That's far too often if we're creating
files very quickly. And it only tried to output a line after entire
directories, so output could stall for very large directories.
Behave more inline with vmstat, iostat, etc, and output a line at a
regular time interval.
Signed-off-by: Zach Brown <zab@versity.com>