swap does not compile

[Benjamin Kosnik]

>Ben, I'll leave the test for the right specialization of swap for
>vectors for you (PR 13658), if you don't mind.  I've no idea of how to
>test for this kind of stuff in the libstdc++ testsuite.

Hi Alexandre! Thanks for fixing this stuff up.

I'll take responsibility for putting these tests in. Unfortunately,
mainline is a bit iffy at the moment so I'll wait till the compiler
settles down before working on this.

thanks!

-benjamin