Add fuzz target for cranelift_reader::parse_test.

cranelift/fuzz/fuzz_reader_parse_test.rs

@@ -0,0 +1,11 @@
+#![no_main]
+#[macro_use]
+extern crate libfuzzer_sys;
+extern crate cranelift_reader;
+use std::str;
+
+fuzz_target!(|data: &[u8]| {
+    if let Ok(s) = str::from_utf8(data) {
+        let _ = cranelift_reader::parse_test(s);
+    }
+});