Fix syntax error in check_arg() function

CHANGELOG

@@ -4,6 +4,7 @@
          - Remove unused variables saarg, csarg, and smarg in
            get_trust_values() function
          - Remove unused CERTLIST variable in copy-trust-modifications
+         - Fix syntax error in check_arg() function
          - Correct STDERR redirection in multiple functions
 1.2      - Use md5sum values for anchors.txt to detect p11-kit changes
          - Added get_p11_label() function to get reliable label values

make-ca

@@ -227,8 +227,8 @@ function get_args(){
 }
 
 function check_arg(){
-  echo "${2}" | grep -v "^-" > /dev/null
-  if [ -z "$?" -o ! -n "$2" ]; then
+  echo "${2}" | grep "^-" > /dev/null
+  if [ "$?" == "0" -o ! -n "$2" ]; then
     echo "Error:  $1 requires a valid argument."
     exit 1
   fi