remove obsolete documentation from the site

[thestinger]

There's the old documentation for libcore under the static subdomain http://static.rust-lang.org/doc/core/index.html and also old documentation under the dl subdomain http://dl.rust-lang.org/doc/tutorial-ffi.html

It would be nice to purge these because they clutter search results, and occasionally people ask about them.

[thestinger]

Another set of them:

http://static.rust-lang.org/doc/core/files/str-rs.html

[thestinger]

The documentation is also still there for old module paths, such as http://static.rust-lang.org/doc/std/dbg.html

[thestinger]

cc @brson - ideally, the doc builder would clear these directories when uploading the replacements

[brson]

Done.

[huonw]

Still appears to be a bug:

• http://static.rust-lang.org/doc/master/extra/url/index.html (new)
• http://static.rust-lang.org/doc/master/extra/url.html (old)

[alexcrichton]

This should be fixed by #9544

[alexcrichton]

Yay! PR has been merged and buildbots have been upated, the old docs no longer exist.