DESCRIPTION

https://github.com/shlomif/perl-XML-LibXML/pull/63

This test program

use warnings;
use XML::LibXML;

my $test = XML::LibXML::Text->new({}->{bar});

produces the following warning:

$ perl ~/test.pl
Use of uninitialized value in subroutine entry at /home/sven/test.pl line 4.

This apparently happens, because Sv2C tries to catch undef values by comparing the memory location of the scalar in question to &PL_sv_undef. While PL_sv_undef certainly is an undef value, not all undef values share its memory location. The added commit fixes this, by using SvOK to correctly detect all undef values.