any (any::operator=(const any&)): Move check for self-assignment.

any (any::operator=(const any&)): Move check for self-assignment.

	* include/experimental/any (any::operator=(const any&)): Move check
	for self-assignment.
	(any::operator=(any&&)): Add check for self-assignment.
	(any::operator=(_ValueType&&)): Constrain template argument.
	(any::swap(any&)): Add check for self-swap.
	* testsuite/experimental/any/assign/self.cc: Test move and swap.
	* testsuite/experimental/any/misc/any_cast_neg.cc: Update dg-error.

From-SVN: r226894