Don't treat attempts to read an already read file list as fatal errors.

* src/names.c (add_file_id): Report error and return 1 if the file
has already been read.
(read_next_name): Don't try to open file if add_file_id returns 1.
(name_next_elt): Simplify conditional.

src/names.c

@@ -325,7 +325,7 @@ struct file_id_list
 
 static struct file_id_list *file_id_list;
 
-static void
+static int
 add_file_id (const char *filename)
 {
   struct file_id_list *p;
@@ -336,14 +336,16 @@ add_file_id (const char *filename)
   for (p = file_id_list; p; p = p->next)
     if (p->ino == st.st_ino && p->dev == st.st_dev)
       {
-	FATAL_ERROR ((0, 0, _("%s: file list already read"),
-		      quotearg_colon (filename)));
+	ERROR ((0, 0, _("%s: file list already read"),
+		quotearg_colon (filename)));
+	return 1;
       }
   p = xmalloc (sizeof *p);
   p->next = file_id_list;
   p->ino = st.st_ino;
   p->dev = st.st_dev;
   file_id_list = p;
+  return 0;
 }
 
 enum read_file_list_state  /* Result of reading file name from the list file */
@@ -424,7 +426,8 @@ read_next_name (struct name_elt *ent, struct name_elt *ret)
 	}
       else
 	{
-	  add_file_id (ent->v.file.name);
+	  if (add_file_id (ent->v.file.name))
+	    return 1;
 	  if ((ent->v.file.fp = fopen (ent->v.file.name, "r")) == NULL)
 	    open_fatal (ent->v.file.name);
 	}