adb: add superfluous include.

Resolve a merge conflict between internal and aosp by making aosp look
like internal.

Test: none
Change-Id: I7bea6ab61ad45ff20a3d07abf3f73903a7c05585
Merged-In: If73b81ca73ba4d64763cf49c1bbe42de81fa1cb6
diff --git a/adb/daemon/auth.cpp b/adb/daemon/auth.cpp
index 1800f84..00268a7 100644
--- a/adb/daemon/auth.cpp
+++ b/adb/daemon/auth.cpp
@@ -18,6 +18,7 @@
 
 #include "adb.h"
 #include "adb_auth.h"
+#include "adb_io.h"
 #include "fdevent.h"
 #include "sysdeps.h"
 #include "transport.h"