[xml] xmlCopyProp() / xmlCopyPropList() don't work properly

["Oliver Stöneberg" <oliverst online de>]

I want to copy a attribute list from one node to another. The 
function xmlCopyPropList() did return a copy of the attributes, but 
it didn't out them into the "target" node. "properties" was still 
NULL.

Same for the function xmlCopyProp().

I tried it with libxml2-2.6.7 and libxml2-2.6.10 on MSVC and MinGW. 
Both show the same behavior.