Version 1.1.42 is available upstream. Please consider updating! It seems that version 1.1.42 is available upstream, while the latest version in the Gentoo tree is 1.1.41. You think this warning is false? Read more about it here.
libxml2-2.13.1 removed "deprecated" symbols that other (older) packages depend upon. It can be mitigated with a --with-legacy configure option, but it's still not a perfect fix. Bug #935452 to track and work on tree-wide support. Masking the exact version so we can revbump the package with a fix.