Fuzzing against verified fork of spec interpreter (#3843)

* Revert "Remove spec interpreter fuzz target temporarily (#3399)"

This reverts commit 25d3fa4d7b.

* add support for differential fuzzing against verified OCaml interpreter

* formatting

* comments

* fix missing dep case

* fix build error

* fix unit tests?

* restore previous differential_v8 max_table config

* attempt: add OCaml deps

* fix interpeter github repo

* fix spec repo url

* fix zarith package

* fix unit test

crates/fuzzing/wasm-spec-interpreter/ocaml/README.md

@@ -1,7 +1,10 @@
 This directory contains the necessary parts for building a library with FFI
 access to the Wasm spec interpreter. Its major parts:
  - `spec`: the Wasm spec code as a Git submodule (you may need to retrieve it:
-   `git clone https://github.com/bytecodealliance/wasm-spec-mirror).
+   `git clone https://github.com/conrad-watt/spec/tree/wasmtime_fuzzing).
  - `interpret.ml`: a shim layer for calling the Wasm spec code and exposing it
    for FFI access
  - `Makefile`: the steps for gluing these pieces together into a static library
+
+Note: the makefile must be configured with the path to libgmp. See LIBGMP_PATHS
+in the makefile.