add bounded-int and pb2bv solvers to fd_solver, use sorting networks for pb2bv rewriter when applicable, hoist to pb2bv_rewriter module and remove it from the pb2bv_tactic

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

contrib/cmake/src/test/CMakeLists.txt

@@ -78,6 +78,7 @@ add_executable(test-z3
   old_interval.cpp
   optional.cpp
   parray.cpp
+  pb2bv.cpp
   pdr.cpp
   permutation.cpp
   polynomial.cpp