Merge pull request #14129 from ZhouyihaiDing/channel_reuse_leak

php: fix channel reuse doesn't free allocated wrapper

src/php/ext/grpc/channel.c

@@ -318,6 +318,10 @@ PHP_METHOD(Channel, __construct) {
         channel->wrapper->creds_hashstr = NULL;
       }
       free(channel->wrapper->creds_hashstr);
+      free(channel->wrapper->key);
+      free(channel->wrapper->target);
+      free(channel->wrapper->args_hashstr);
+      free(channel->wrapper);
       channel->wrapper = le->channel;
     }
   }