[utils] Add script to remove all empty test directories

After having checked out an older commit, e.g. during bisect, and then
checking out another commit, test directories that are deleted still
exists since they might contain leftover files (output, log, ...)

These cause "make tests" to fail, since it cannot run that test.

utils/clean-tests

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+cd `dirname $(readlink -f $0)`/../src
+
+# Hitta alla mappar som börjar med "test_"
+for dir in test_*; do
+    # Kontrollera om det finns några git-kontrollerade filer, Makefile eller .suspended
+    # för då är de antingen äkta test-mappar eller en som inte ännu inte fungerar
+    # annars kan vi ta bort den
+    if [ -z "$(git ls-files "$dir")" ] && [ ! -f "$dir/Makefile" ] && [ ! -f "$dir/.suspended" ]; then
+        rm -rf $dir
+        echo "Removed $dir"
+    fi
+done