MacOSX libxml2/libxslt sdk versions ?

I was considering bumping our libxmlsec to the latest version of that
(1.2.14). But libxmlsec requires a libxml2 >= 2.7.6. Bumping our
internal versions to the latest libxml2 and libxslt isn't a problem in
itself, and probably a good thing to do. 

But I see that our Mac OSX config defaults to system libxml2 and I can
tell from the buildbots that the MacOSX libxml2 is of a lower level than
2.7.6. From the previous discussion around curl I imagine that the
system libxml2 on Mac that OOo uses by default comes from the Mac 10.4
SDK right ? And that a goal is to try and keep Mac's requirements to the
Mac SDK 10.4 baseline. So, is there a list of the versions of libraries
in that SDK ? 

C.