build: Fixes wrong use of __has_include for optionals
build: Fixes wrong use of __has_include for optionals

The header exists on versions of the STL shipped with recent compilers
but it doesn't mean the feature is available.

Change-Id: I0824a99ef199d2c9b1eb208d66bbd51ed1925edd
Reviewed-on: http://gerrit.aldebaran.lan/90014
Reviewed-by: vincent.palancher <f8ff75e1c61314c499fafa8de0d9e004e87e66b0@external.softbankrobotics.com>
Reviewed-by: jmonnon <8898eaf233516e520f996a244ca8a12d20f948b1@aldebaran.com>
Reviewed-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>
Tested-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi