A simplified model of Fil-C

I made https://github.com/hsaliak/filc-bazel-template bazel target for people who may want to use these two together to make hermetic builds with it.

Fil-C is one of the most underrated projects I've ever seen. All this "rewrite it in rust for safety" just sounds stupid when you can compile your C program completely memory safe.

This is yet another variant of the "fat pointers" technique, which has been implemented and rejected many times due to either insufficient security guarantees, inability to cross non-fat ABI boundaries, or the overhead it introduces.