media kit: avoid useless copy of entry_ref

Copying an entry_ref is not cheap since the "name" field needs to be
allocated and copied separately everytime. Here it is not needed at all,
so let's just use a reference instead.

Change-Id: I1e572b69569cbb7437db147b483779245ec5e180

src/kits/media/PluginManager.cpp

@@ -234,7 +234,7 @@ PluginManager::CreateReader(Reader** reader, int32* streamCount,
 
 	// try each reader by calling it's Sniff function...
 	for (int32 i = 0; i < count; i++) {
-		entry_ref ref = refs[i];
+		const entry_ref& ref = refs[i];
 		MediaPlugin* plugin = GetPlugin(ref);
 		if (plugin == NULL) {
 			printf("PluginManager::CreateReader: GetPlugin failed\n");