Fix undefined symbol errors caused by mixing the v8 headers bundled with
nodejs with the system v8 libraries. Changes taken from/inspired by Fedora,
except my install.py patch, which I wrote myself.

I did not integrate, but it may be worth considering, the v8 ABI deps
Fedora uses. At the very least we need to make sure nodejs gets rebuilt
after a libv8 version bump (e.g. 3.15.x to 3.16.x, not necessary for
3.16.x to 3.16.y).