[xmlsec] exc c14n w/o comments bug

[xs04.jmdesp at free.fr]

Quoting Tomas Sieger <tomas.sieger at systinet.com>:
>   you are absolutely right: I tested the old version of libxml2 :-(. The 
> patched version seems to be ok.

Well the patch does seem effective with testC14N, but I still get the wrong c14
when running "xmlsec -sign" with "--store-references".

I even runned xmlsec in the debugger to make sure it's really the modified
version of nodeset.c that's executed.