hashtable_policy.h (_Hashtable_alloc): New.

2013-08-06  François Dumont  <fdumont@gcc.gnu.org>

	* include/bits/hashtable_policy.h (_Hashtable_alloc): New.
	(_ReuseOrAllocNode, _AllocNode): Adapt to use latter rather than
	_Hashtable.
	(_Before_begin<>): Remove.
	* include/bits/hashtable.h (_Hashtable): Inherit from
	_Hashtable_alloc and adapt. Restore _M_before_begin field.
	* python/libstdcxx/v6/printers.py (StdHashtableIterator): Adapt
	access to hashtable before begin.
	* testsuite/23_containers/unordered_set/
	not_default_constructible_hash_neg.cc: Adapt dg-error line number.
	* testsuite/23_containers/unordered_set/instantiation_neg.cc:
	Likewise.

From-SVN: r201522