Optimize hashtable allocator

[Jonathan Wakely]

This fixes the hashtable and forward_list printers.

Tested x86_64-linux, committed to trunk.
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commit 2f8ec0a8fa9dfca88259fb3a3273884939868bae
Author: Jonathan Wakely <jwakely.gcc@gmail.com>
Date:   Fri Nov 2 01:41:37 2012 +0000

    	* python/libstdcxx/v6/printers.py (Tr1HashtableIterator): Update.
    	(StdForwardListPrinter): Likewise.

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 07a5ee6..5197284 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -612,7 +612,7 @@ class StdStringPrinter:
 
 class Tr1HashtableIterator:
     def __init__ (self, hash):
-        self.node = hash['_M_before_begin']['_M_nxt']
+        self.node = hash['_M_bbegin']['_M_node']['_M_nxt']
         self.node_type = find_type(hash.type, '__node_type').pointer()
 
     def __iter__ (self):
@@ -707,7 +707,9 @@ class StdForwardListPrinter:
             self.base = elt['_M_next']
             count = self.count
             self.count = self.count + 1
-            return ('[%d]' % count, elt['_M_value'])
+            valptr = elt['_M_storage'].address
+            valptr = valptr.cast(elt.type.template_argument(0).pointer())
+            return ('[%d]' % count, valptr.dereference())
 
     def __init__(self, typename, val):
         self.val = val