optutils.h: don't print non-graph characters

optutils.h: don't print non-graph characters

There is no eloquent way to exclude/include arch dependent arguments
from the ul_excl_t array. So when an arch dependent argument is left
undefined err_exclusive_options() was printing out-of-bounds values.
This commit cause them to be skipped instead.

err_exclusive_options() shouldn't be printing out-of-bounds values
in any case.

Also change the error massage from 'options' to 'arguments' as some
programs, like hwclock, distinguish between options and functions.

Signed-off-by: J William Piggott <elseifthen@gmx.com>