[v3 PATCH] Fix the constraints for any's assignment operator template to properly reject assignment from a non-copyable lvalue.

[Jonathan Wakely]

On 14/07/16 20:27 +0300, Ville Voutilainen wrote:
>    Fix the constraints for any's assignment operator template to properly
>    reject assignment from a non-copyable lvalue.
>    * include/std/any (operator=(_ValueType&&)): Constrain the decayed
>    type for is_copy_constructible,
>    * testsuite/20_util/any/requirements.cc: Add a test for
>    non-copyable lvalues.

OK for trunk, thanks.