Experiment with cargo fuzz

This seems to find at least some issues, which I'll investigate.

vobsub/fuzz/.gitignore

@@ -0,0 +1,5 @@
+
+target
+libfuzzer
+corpus
+artifacts

vobsub/fuzz/Cargo.toml

@@ -0,0 +1,22 @@
+
+[package]
+name = "vobsub-fuzz"
+version = "0.0.1"
+authors = ["Automatically generated"]
+publish = false
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies.vobsub]
+path = ".."
+[dependencies.libfuzzer-sys]
+git = "https://github.com/rust-fuzz/libfuzzer-sys.git"
+
+# Prevent this from interfering with workspaces
+[workspace]
+members = ["."]
+
+[[bin]]
+name = "fuzzer_script_1"
+path = "fuzzers/fuzzer_script_1.rs"

vobsub/fuzz/fuzzers/fuzzer_script_1.rs

@@ -0,0 +1,11 @@
+#![no_main]
+
+extern crate libfuzzer_sys;
+extern crate vobsub;
+
+#[export_name="rust_fuzzer_test_input"]
+pub extern fn go(data: &[u8]) {
+    for _ in vobsub::subtitles(data) {
+        // Just parse and ignore.
+    }
+}