onCleanPendingMessage: Avoid costly copy by holding lock longer.
onCleanPendingMessage: Avoid costly copy by holding lock longer.

Do not copy the pendingMessage map. It means we must hold the lock
while invoking callbacks.
10% gain in perf_transport

Change-Id: I4b7d6155af8187553579b60e0eeb8dc2185de843
Reviewed-on: http://gerrit.aldebaran.lan:8080/3761
Reviewed-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi-java,bsautron/libqi,aldebaran/libqi-java,vbarbaresi/libqi,aldebaran/libqi,aldebaran/libqi,aldebaran/libqi-java