merge from gcc

include/hashtab.h

@@ -81,6 +81,15 @@ typedef void (*htab_free) (void *);
 typedef void *(*htab_alloc_with_arg) (void *, size_t, size_t);
 typedef void (*htab_free_with_arg) (void *, void *);
 
+/* This macro defines reserved value for empty table entry.  */
+
+#define HTAB_EMPTY_ENTRY    ((PTR) 0)
+
+/* This macro defines reserved value for table entry which contained
+   a deleted element. */
+
+#define HTAB_DELETED_ENTRY  ((PTR) 1)
+
 /* Hash tables are of the following type.  The structure
    (implementation) of this type is not needed for using the hash
    tables.  All work with hash table should be executed only through