rql #49053 Swallow CompilationError in setup.py [validation pending]

rql uses ``logilab.constraint`` if the gecode extension is not avaible and ``logilab.constraint`` is a dependancy. So, ``python setup.py install`` may not fail on CompilationError.

prioritynormal
typebug
done in0.29.0
load0.250
load left0.000
closed by<not specified>