Fix shellcheck warning

$@ is only supposed to be used as "$@", for all uses within strings, $*
is the correct variable.

mpbb-install-port

@@ -38,7 +38,7 @@ install-port() {
     # $option_prefix and $thisdir are set in mpbb
     # shellcheck disable=SC2154
     if [[ -f $("${option_prefix}/bin/port-tclsh" "${thisdir}/tools/archive-path.tcl" "$@") ]]; then
-        echo "$@ already installed, nothing to do"
+        echo "$* already installed, nothing to do"
         # log: summary for the portwatcher
         echo "Building '$port' ... [OK]" >> "$log_subports_progress"
         echo "$@" >> "${option_work_dir}/all_ports"