The configure.ac script doesn't check for xt.pc, so if libxt-dev (or whatever is the name on other distros) is missing the configure stage passes but the build fails at compile time.
Created attachment 22635 [details]
Check for xt.pc
This is a duplicate of https://bugs.webkit.org/show_bug.cgi?id=19045. Perhaps update the patch that's already in there? You might want to look at Holger's comment as well (though you've already covered the first bit :)
*** This bug has been marked as a duplicate of 19045 ***