scripts: Add script to list unused test files

This script will search through all the tests and look for files that
aren't used, printing them out. It doesn't look at all.sh or other tests
yet, just the test suites for now.

Author: Patater

scripts/list-unused-test-files.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+# Abort on errors (and uninitialised variables)
+set -eu
+
+if [ -d library -a -d include -a -d tests ]; then :; else
+    echo "Must be run from mbed TLS root" >&2
+    exit 1
+fi
+
+ls tests/data_files | \
+    while read f; do
+        grep -R -F --exclude=Makefile "$f" tests >/dev/null || echo "$f"
+    done