adbd: use libadbd_auth for authentication.

Bug: http://b/137798163
Test: for i in `seq 1 100000`; do echo $i; adb wait-for-device shell "su 0 stop; su 0 start; sleep 10"; adb disconnect; done
Change-Id: Ie481e79a48c4aabf18ef797317ba18f207808c63
diff --git a/adb/transport.h b/adb/transport.h
index c38cb1d..89d76b8 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -277,8 +277,11 @@
     std::string device;
     std::string devpath;
 
+#if !ADB_HOST
     // Used to provide the key to the framework.
     std::string auth_key;
+    uint64_t auth_id;
+#endif
 
     bool IsTcpDevice() const { return type == kTransportLocal; }