Recover the memory info for known symbols

Instead of querying gdb again.

Author: petr-bauch

src/memory-analyzer/analyze_symbol.cpp

@@ -490,7 +490,11 @@ exprt gdb_value_extractort::get_pointer_value(
   PRECONDITION(expr.type() == zero_expr.type());
 
   std::string c_expr = c_converter.convert(expr);
-  const pointer_valuet value = gdb_api.get_memory(c_expr);
+  const auto known_pointer = memory_map.find(c_expr);
+
+  pointer_valuet value = known_pointer == memory_map.end()
+                           ? gdb_api.get_memory(c_expr)
+                           : known_pointer->second;
   if(!value.valid)
     return zero_expr;