more error checking for hash builtin; fix for [[ builtin and some test syntax errors

hashcmd.c

@@ -66,9 +66,12 @@ phash_remove (const char *filename)
 {
   register BUCKET_CONTENTS *item;
 
-  if (hashing_enabled == 0 || hashed_filenames == 0)
+  if (hashing_enabled == 0)
     return 0;
 
+  if (hashed_filenames == 0)
+    return 1;
+
   item = hash_remove (filename, hashed_filenames, 0);
   if (item)
     {