ensure variable structure is initialized before use (issue #5092)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6494 65c4cc65-6c06-0410-ace0-fbb531ad65f3

chanvars.c

@@ -40,6 +40,7 @@ struct ast_var_t *ast_var_assign(const char *name, const char *value)
 		return NULL;
 	}
 	
+	memset(var, 0, len);
 	i = strlen(name);
 	strncpy(var->name, name, i); 
 	var->name[i] = '\0';