Add a log message that appears when you try to unload a module that isn't loaded.

(closes issue #12033)
Reported by: jamesgolovich
Patches:
      asterisk-loader.diff.txt uploaded by jamesgolovich (license 176)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@103828 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/loader.c

@@ -478,6 +478,7 @@ int ast_unload_resource(const char *resource_name, enum ast_module_unload_mode f
 
 	if (!(mod = find_resource(resource_name, 0))) {
 		AST_LIST_UNLOCK(&module_list);
+		ast_log(LOG_WARNING, "Unload failed, '%s' could not be found\n", resource_name);
 		return 0;
 	}