Make bash function syntax consistent with other scripts in the repo.

lib/cretonne/meta/check.sh

@@ -2,7 +2,7 @@
 set -euo pipefail
 cd $(dirname "$0")
 
-runif() {
+function runif() {
     if command -v "$1" > /dev/null; then
         echo "   === $1 ==="
         "$@"