[xmlsec] Typo in configure.js

[Jesse Pelton]

The usage() function in xmlsec-0.0.12\win32\configure.js includes the
following line:

 	txt += "  xslt:       LibXSLT is not used (" + (withLibXSLT? "yes" :
"no")  + ")\n";

I believe this should read "...LibXSLT is used..." The logic is positive, as
for other options, not negative, as the text states.