Tidy up and document

Author: TGWDB

src/goto-symex/goto_state.h

@@ -12,7 +12,6 @@ Author: Romain Brenguier, [email protected]
 #ifndef CPROVER_GOTO_SYMEX_GOTO_STATE_H
 #define CPROVER_GOTO_SYMEX_GOTO_STATE_H
 
-#include <unordered_map>
 #include <util/sharing_map.h>
 
 #include <analyses/guard.h>

src/goto-symex/symex_config.h

@@ -59,6 +59,7 @@ struct symex_configt final
   ///   dereference with a single symbol that contains the result of that
   ///   dereference. Can sometimes lead to a significant performance
   ///   improvement, but sometimes also makes things worse.
+  ///   See https://github.com/diffblue/cbmc/pull/5964 for performance data.
   ///   Used in goto_symext::dereference_rec
   bool cache_dereferences;