tests: port proptest fuzz harnesses to use cargo-fuzz (#5392)

This change ports fuzz tests from the black-box fuzzing framework,
proptest-rs over to use the grey-box fuzzing framework cargo-fuzz.

Refs: #5391

tokio/fuzz/.gitignore

@@ -0,0 +1,4 @@
+target
+corpus
+artifacts
+coverage

tokio/fuzz/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "tokio-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2018"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+
+[dependencies.tokio]
+path = ".."
+features = ["fs","net","process","rt","sync","signal","time"]
+
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[profile.release]
+debug = 1
+
+[[bin]]
+name = "fuzz_linked_list"
+path = "fuzz_targets/fuzz_linked_list.rs"
+test = false
+doc = false

tokio/fuzz/fuzz_targets/fuzz_linked_list.rs

@@ -0,0 +1,7 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    tokio::fuzz::fuzz_linked_list(data);
+});