add outline for ule constraints, change bit to var constraints

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/math/polysat/CMakeLists.txt

@@ -2,7 +2,8 @@ z3_add_component(polysat
   SOURCES
     constraint.cpp
     eq_constraint.cpp
-    bit_constraint.cpp
+    ule_constraint.cpp
+    var_constraint.cpp
     justification.cpp
     log.cpp
     solver.cpp