ext/xmlrpc using libxml2

I was playing around with the compile of xmlrpc using libxml2

    and got it to somewhat work (more about that later :).

    I took the shortcut of using the compatibility layer which is
    used by ext/xml (compat.c and expat_compat.h).

    Now, before I commit this stuff I'd like to know if this is
    even wanted result? Or should the whole thing be converted
    to really use libxml2 without any layers between?

    About the "somewhat work" part: It works as long as there aren't
    any errors with the XML. :) When there are, the thing just hangs.
    Backtrace showed it hangs somewhere inside xmlParseChunk()..

    --Jani