Create a new wasmtime-fuzzing crate

This crate is intended to hold all of our various test case generators and
oracles. The fuzz targets we have at `wasmtime/fuzz/fuzz_targets/*` will
eventually be ~one-liner glue code calling into this crate.

Part of #611

Cargo.toml

@@ -54,6 +54,7 @@ anyhow = "1.0.19"
 
 [workspace]
 members = [
+  "crates/fuzzing",
   "crates/misc/rust",
   "crates/misc/py",
 ]

crates/fuzzing/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+authors = ["The Wasmtime Project Developers"]
+description = "Fuzzing infrastructure for Wasmtime"
+edition = "2018"
+name = "wasmtime-fuzzing"
+publish = false
+version = "0.1.0"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

crates/fuzzing/README.md

@@ -0,0 +1,14 @@
+# Fuzzing Infrastructure for Wasmtime
+
+This crate provides test case generators and oracles for use with fuzzing.
+
+These generators and oracles are generally independent of the fuzzing engine
+that might be using them and driving the whole fuzzing process (e.g. libFuzzer
+or AFL). As such, this crate does *not* contain any actual fuzz targets
+itself. Those are generally just a couple lines of glue code that plug raw input
+from (for example) `libFuzzer` into a generator, and then run one or more
+oracles on the generated test case.
+
+If you're looking for the actual fuzz target definitions we currently have, they
+live in `wasmtime/fuzz/fuzz_targets/*` and are driven by `cargo fuzz` and
+`libFuzzer`.