Fix the sense of a test in "adb sideload".

            android::base::StringPrintf("sideload-host:%d:%d", sz, SIDELOAD_HOST_BLOCK_SIZE);

    std::string error;

    unique_fd fd(adb_connect(service, &error));

    if (fd >= 0) {

    if (fd < 0) {

        // Try falling back to the older sideload method.  Maybe this

        // is an older device that doesn't support sideload-host.

        printf("\n");