QupZilla: Address Oliver's review comment.

My patch was upstreamed, so we now can point there.
Ruby: inform autoconf where the private (elf32/elf64) headers are.

Now the build fails because SIGBUS is undeclared...
Ruby: get the miniruby part to compile...

...but it crashes when trying to execute something. Oh well, that's
at least better than when it never compiled at all, I suppose.