Use more straightforward style to check if array's empty

Author: Antiz96

package/greposcope

@@ -65,7 +65,7 @@ mkdir -p "${tmp_dir}"
 echo -e "==> Fetching the list of unreproducible packages...\n"
 mapfile -t pkg_list < <(rebuildctl -H "${rebuilderd_host}" pkgs ls --status BAD | awk '{print $3}')
 
-if [ ${#pkg_list[@]} -eq 0 ]; then
+if ! (( ${#pkg_list[@]} )); then
 	echo "==> No unreproducible packages found"
 	exit 0
 fi
@@ -79,7 +79,7 @@ done
 
 pkg_list=("${updated_pkg_list[@]}")
 
-if [ ${#pkg_list[@]} -eq 0 ]; then
+if ! (( ${#pkg_list[@]} )); then
 	echo "==> All diffoscope outputs are already downloaded"
 else
 	echo -e "==> Downloading diffoscope outputs of ${#pkg_list[@]} unreproducible packages...\nThis may take some time...\n"