Use CPROVER_SMT2 for loop acceleration

Author: SaswatPadhi

src/goto-instrument/accelerate/scratch_program.h

@@ -77,8 +77,8 @@ class scratch_programt:public goto_programt
       symex(mh, symbol_table, equation, options, path_storage, guard_manager),
       satcheck(util_make_unique<satcheckt>(mh)),
       satchecker(ns, *satcheck, mh),
-      z3(ns, "accelerate", "", "", smt2_dect::solvert::Z3, mh),
-      checker(&z3) // checker(&satchecker)
+      solver(ns, "accelerate", "", "", smt2_dect::solvert::CPROVER_SMT2, mh),
+      checker(&solver) // checker(&satchecker)
   {
   }
 
@@ -116,7 +116,7 @@ class scratch_programt:public goto_programt
 
   std::unique_ptr<propt> satcheck;
   bv_pointerst satchecker;
-  smt2_dect z3;
+  smt2_dect solver;
   decision_proceduret *checker;
   static optionst get_default_options();
 };