Add mDNS device discovery for adb client

Test: Was able to discover a raspberry pi.
Bug: 28074466
(cherry picked from e292cd16760321fccc99c8c261cb92fa4b6462ab)

Change-Id: Id9571576457a4a0a078e48a274a4e8eac78bfe2b
diff --git a/adb/daemon/mdns.cpp b/adb/daemon/mdns.cpp
index a8622ae..7811143 100644
--- a/adb/daemon/mdns.cpp
+++ b/adb/daemon/mdns.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "adb_mdns.h"
 #include "sysdeps.h"
 
 #include <chrono>