adb: update symlink timestamps.

Bug: http://b/120162375
Test: adb sync; adb shell touch -h -d 2008-01-0101:01:01 /system/bin/ls; adb sync; adb sync
Change-Id: Iedf54528b164913739c66c71d20006e484a4f5e4
diff --git a/adb/transport.h b/adb/transport.h
index 065c81f..a0174b8 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -67,6 +67,8 @@
 extern const char* const kFeatureFixedPushMkdir;
 // adbd supports android binder bridge (abb).
 extern const char* const kFeatureAbb;
+// adbd properly updates symlink timestamps on push.
+extern const char* const kFeatureFixedPushSymlinkTimestamp;
 
 TransportId NextTransportId();