Adding new feature to adb "abb".

It will allow clients to detect if abb is supported.

Test: manual
BUG: 111621042

Change-Id: Ifddabe49214882a6c6ad898c7e2a0f5cc92458d8
diff --git a/adb/transport.h b/adb/transport.h
index 790004f..6f53e6e 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -64,6 +64,8 @@
 extern const char* const kFeatureApex;
 // adbd has b/110953234 fixed.
 extern const char* const kFeatureFixedPushMkdir;
+// adbd supports android binder bridge (abb).
+extern const char* const kFeatureAbb;
 
 TransportId NextTransportId();