adbd: avoid compiling more code in the daemon.

Strip out more code that has no meaning on device, to "improve"
coverage.

Test: test_device.py over TCP
Change-Id: Id8d9fa6cc6c6c30773f67303bcc89e6d60824700
diff --git a/adb/adb.cpp b/adb/adb.cpp
index dcec0ba..08986b7 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -109,7 +109,9 @@
 {
     D("adb: online");
     t->online = 1;
+#if ADB_HOST
     t->SetConnectionEstablished(true);
+#endif
 }
 
 void handle_offline(atransport *t)