libbinder: RPC disambiguate server/client

Now:
- server: RpcServer
- client: a client of an RpcServer
- incoming: a thread processing commands (either as part of an
  RpcServer's sessions or back to a client which has a threadpool)
- outgoing: a thread for sending commands (either to an RpcServer's
  sessions or back to a client which has a threadpool)

Bug: 167966510
Test: binderRpcTest
Change-Id: Iea286ab0ff6f9fb775994247003b8d29c999e10a
diff --git a/libs/binder/RpcWireFormat.h b/libs/binder/RpcWireFormat.h
index b5e5bc1..92da856 100644
--- a/libs/binder/RpcWireFormat.h
+++ b/libs/binder/RpcWireFormat.h
@@ -43,7 +43,7 @@
  * transaction. The main use of this is in order to control the timing for when
  * a reverse connection is setup.
  */
-struct RpcClientConnectionInit {
+struct RpcOutgoingConnectionInit {
     char msg[4];
     uint8_t reserved[4];
 };