In one exit path we forgot to free the virNetMessage object causing
a large memory leak for streams which send a lot of data. Some other
paths were calling VIR_FREE directly instead of virNetMessageFree
although this was (currently) harmless.

* src/rpc/virnetclientstream.c: Fix leak of msg object
* src/rpc/virnetclientprogram.c: Call virNetMessageFree instead
  of VIR_FREE