Fix OutOfFuel trap code not represented in the C API. (#5230)

This commit adds the missing "out of fuel" trap code to the C API.

Without this, calls to `wasmtime_trap_code` will trigger an unreachable panic
on traps from running out of fuel.

examples/fuel.c

@@ -100,6 +100,11 @@ int main() {
     wasmtime_val_t results[1];
     error = wasmtime_func_call(context, &fib.of.func, params, 1, results, 1, &trap);
     if (error != NULL || trap != NULL) {
+      if (trap != NULL) {
+        wasmtime_trap_code_t code;
+        assert(wasmtime_trap_code(trap, &code));
+        assert(code == WASMTIME_TRAP_CODE_OUT_OF_FUEL);
+      }
       printf("Exhausted fuel computing fib(%d)\n", n);
       break;
     }

examples/fuel.rs

@@ -20,7 +20,8 @@ fn main() -> Result<()> {
         let fuel_before = store.fuel_consumed().unwrap();
         let output = match fibonacci.call(&mut store, n) {
             Ok(v) => v,
-            Err(_) => {
+            Err(e) => {
+                assert_eq!(e.downcast::<Trap>()?, Trap::OutOfFuel);
                 println!("Exhausted fuel computing fib({})", n);
                 break;
             }