fix openbsd color-display problem in system test output

bin/tests/system/conf.sh.in

@@ -163,7 +163,7 @@ NZD=@NZD_TOOLS@
 #
 # Set up color-coded test output
 #
-if [ ${SYSTEMTEST_FORCE_COLOR:-0} -eq 1 ] || test -t 1 && type tput > /dev/null 2>&1 ; then
+if [ ${SYSTEMTEST_FORCE_COLOR:-0} -eq 1 ] || test -t 1 && type tput > /dev/null 2>&1 && tput setaf 7 > /dev/null 2>&1 ; then
     COLOR_END=`tput setaf 4`    # blue
     COLOR_FAIL=`tput setaf 1`   # red
     COLOR_INFO=`tput bold`      # bold