[C++0x patch] move construct std::function target

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

This patch implements the requirement that std::function
move-constructs its target object, as well as my proposed resolution
to LWG issue 1288, see
http://home.roadrunner.com/~hinnant/issue_review/lwg-active.html#1288

I've added __throw_bad_function_call, which I'm also going to use in
std::packaged_task in another patch coming soon.


	* include/std/functional (function::function): Move construct target.
	(function::operator=): Use perfect forwarding for argument.
	(function::operator()): Use new __throw_bad_function_call.
	* include/bits/functexcept.h (__throw_bad_function_call): Declare.
	* src/functexcept.cc (__throw_bad_function_call): Define.
	* config/abi/pre/gnu.ver: Add new symbol.
	* testsuite/20_util/function/cons/move_target.cc: New.
	* testsuite/20_util/function/assign/move_target.cc: New.


Tested x86_64/Linux and committed.

Attachment: function_move_target.txt
Description: Text document