Use default comparer for sorting supports in DiscreteHistogram

[kimsey0]

This is for example relevant for StandardDiscreteUniform, which changes from

 0|***************************************
 1|***************************************
 2|**************************************
 3|***************************************
-1|***************************************
-2|***************************************
-3|****************************************

to

-3|****************************************
-2|***************************************
-1|***************************************
 0|***************************************
 1|**************************************
 2|***************************************
 3|**************************************