Remove unused propogationt::valuest variable

Author: romainbrenguier

src/goto-instrument/accelerate/scratch_program.cpp

@@ -35,8 +35,6 @@ bool scratch_programt::check_sat(bool do_slice)
   output(ns, "scratch", std::cout);
 #endif
 
-  goto_symex_statet::propagationt::valuest constants;
-
   symex.symex_with_state(symex_state, functions, symex_symbol_table);
 
   if(do_slice)