Adds vs benchmark WasmEdge and splits compile from instantiate (#495)

Signed-off-by: Adrian Cole <adrian@tetrate.io>

config.go

@@ -131,11 +131,16 @@ type CompiledCode struct {
 	compiledEngine wasm.Engine
 }
 
+// compile-time check to ensure CompiledCode implements io.Closer (consistent with api.Module)
+var _ io.Closer = &CompiledCode{}
+
 // Close releases all the allocated resources for this CompiledCode.
 //
-// Note: it is safe to call Close while having outstanding calls from Modules instantiated from this *CompiledCode.
-func (c *CompiledCode) Close() {
+// Note: It is safe to call Close while having outstanding calls from Modules instantiated from this *CompiledCode.
+func (c *CompiledCode) Close() error {
 	c.compiledEngine.DeleteCompiledModule(c.module)
+	// It is possible the underlying may need to return an error later, but in any case this matches api.Module.Close.
+	return nil
 }
 
 // ModuleConfig configures resources needed by functions that have low-level interactions with the host operating system.