cmake: make BOOST_LOCALE dependency optional
cmake: make BOOST_LOCALE dependency optional

Change-Id: Ib6309d20711bbf40f6dbf0b916e68a2f69223336
Reviewed-on: http://gerrit.aldebaran.lan/20683
Reviewed-by: proullon <ffff9135679d397f48dd743107119b1f6fc32d3d@aldebaran-robotics.com>
Tested-by: gerrit
Reviewed-on: http://gerrit.aldebaran.lan/21422

aldebaran/libqi,vbarbaresi/libqi,bsautron/libqi,aldebaran/libqi,aldebaran/libqi