future: Removes memory pool.
future: Removes memory pool.

The pool was never shrunk, resulting in ever increasing memory. This problem
is particularly salient in case of message receiving bursts.

This patch must be tested in real context to prove its value.

This is to mitigate issues #43516 and #43454.

Change-Id: Ibca5ba6c4a344d42cfdcc0e83f366cacd5d87827
Reviewed-on: http://gerrit.aldebaran.lan/94086
Reviewed-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>
Reviewed-by: vincent.palancher <f8ff75e1c61314c499fafa8de0d9e004e87e66b0@external.softbankrobotics.com>
Reviewed-by: jmonnon <8898eaf233516e520f996a244ca8a12d20f948b1@aldebaran.com>
Tested-by: jmonnon <8898eaf233516e520f996a244ca8a12d20f948b1@aldebaran.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi