exC: make script executable

exercises/exerciseC/run_with_all_configurations.sh

@@ -1,9 +1,13 @@
-# This is bash
-# It runs the python script multiple times with different arguments
+#!/bin/bash
+set -ex
+
+# This is a bash script.
+# It runs the python program multiple times with different arguments.
+
 for i in {1..5}  # Number of processes
 do
     for j in {1..5}  # Number of threads
     do
         python process_images.py $i $j images/*
     done
-done
+done