support SIMD fuzzing in reference interpreter (#3980)

* support SIMD fuzzing in reference interpreter

* formatting

fuzz/fuzz_targets/differential_spec.rs

@@ -23,6 +23,7 @@ fn run(data: &[u8]) -> Result<()> {
 
     // Enable features that the spec interpreter has implemented
     config.module_config.config.multi_value_enabled = false;
+    config.module_config.config.simd_enabled = true;
 
     // TODO: this is a best-effort attempt to avoid errors caused by the
     //       generated module exporting no functions.