libbinder: update 'TODO' comments for RPC

Some stale/duplicated removed. Some bug numbers updated. Some added
based on what I've been thinking about.

Bug: N/A
Test: N/A
Change-Id: I963bec5085b4d6868126d90c12c62cd64f31ddc0
diff --git a/libs/binder/RpcState.cpp b/libs/binder/RpcState.cpp
index 3113841..6899981 100644
--- a/libs/binder/RpcState.cpp
+++ b/libs/binder/RpcState.cpp
@@ -400,6 +400,8 @@
     if (status_t status =
                 rpcSend(fd, session, "transaction", transactionData.data(), transactionData.size());
         status != OK)
+        // TODO(b/167966510): need to undo onBinderLeaving - we know the
+        // refcount isn't successfully transferred.
         return status;
 
     if (flags & IBinder::FLAG_ONEWAY) {