Look up the class name when registering an alias.

In the v1 ABI, this function is called with the class symbol directly,
so we need to make sure that we replace it with the upgraded symbol.

alias_table.c

@@ -106,6 +106,8 @@ BOOL class_registerAlias_np(Class class, const char *alias)
 		return 0;
 	}
 
+	class = (Class)objc_getClass(class->name);
+
 	/*
 	 * If there already exists a matching alias, determine whether we the existing
 	 * alias is the correct one. Please note that objc_getClass() goes through the