Expand modules instantiated in instantiate-wasm-smith

This commit uses the new `MaybeInvalidModule` type in `wasm-smith` to
try to explore more points in the fuzz target space in the
`instantiate-maybe-invalid` fuzz target. The goal here is to use the raw
fuzz input as the body of a function to stress the validator/decoder a
bit more, and try to get inputs we might not otherwise generate.

fuzz/Cargo.toml

@@ -17,7 +17,7 @@ target-lexicon = "0.10"
 peepmatic-fuzzing = { path = "../cranelift/peepmatic/crates/fuzzing", optional = true }
 wasmtime = { path = "../crates/wasmtime" }
 wasmtime-fuzzing = { path = "../crates/fuzzing" }
-wasm-smith = "0.1.3"
+wasm-smith = "0.1.5"
 
 [[bin]]
 name = "compile"

fuzz/fuzz_targets/instantiate-maybe-invalid.rs

@@ -0,0 +1,15 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use std::time::Duration;
+use wasm_smith::Module;
+use wasmtime::Strategy;
+use wasmtime_fuzzing::oracles;
+
+fuzz_target!(|module: MaybeInvalidModule| {
+    oracles::instantiate_with_config(
+        &module.to_bytes(),
+        wasmtime_fuzzing::fuzz_default_config(Strategy::Auto),
+        Some(Duration::from_secs(20)),
+    );
+});