There is an implicit build-dep on build-essential, which depends on g++ and others. At least there was when I created the rules, I have to check that.
I'm sure you get this error message. When you point your browser at this URL, you'll see that there are only pkg's for i386, not for 64 bit. If you use there source-repo, you should be able to create the needed libupnp.
Which text editor did you use? When I point konqueror at the contents.gz, it just asks me if I want to save it or open it with ark. And file is sure that it's a gzipped file. Just the Release-file is text-only.