shared_from_this documentation: missing semicolon in example code

[dk.boost@…]

The example code in the documentation for shared_from_this is missing a ';' after the '}' that ends class Y:

http://www.boost.org/doc/libs/1_40_0/libs/smart_ptr/enable_shared_from_this.html

[mloskot <mateusz@…>]

Also, it is example and as such it's supposed to be complete to just copy & paste & compile, so boost:: qualification or

using namespace boost;

is missing.

[Peter Dimov]

(In [57950]) Fix enable_shared_from_this example. Refs #3404.

[Peter Dimov]

(In [57959]) Merge [57950], [57952] to release. Fixes #3404. Fixes #3456.