[xml] Build libxml2 Windows

[Patrick von Reth <patrick vonreth gmail com>]

Hi

to build libxml2 I had to patch the build system a little bit.

The windows build system tries to link about zdll, but on windows its called zlib* too, so linking against z is enough.

Also the --include and the --lib command was ignored.

For the http and ftp stuff linking against some windows library's was forgotten for mingw.

In the msvc build script the + in some lines prevented building because of a parser error in nmake.

I hope this will help you to improve your build system.

Cheers Patrick