Update to WebKitGTK 2.43.2

We will have to disable the new libbacktrace dependency. I considered adding it to gnome-build-meta, but it looks like this project has never had any releases ever, so it seems like a questionable dependency.

This also patches perl to enable 64-bit integers to avoid a bug that caused the WebKitGTK build to infinite loop: https://bugs.webkit.org/show_bug.cgi?id=265554

Debugging this was a nightmare but I eventually succeeded thanks to Abderrahim, Seppo, and Jordan. Thank you!